wasCSharpSQLite – Rev 1
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#define SQLITE_MAX_EXPR_DEPTH
using System;
using System.Diagnostics;
using System.Text;
using i16 = System.Int16;
using u8 = System.Byte;
using u16 = System.UInt16;
using u32 = System.UInt32;
using Pgno = System.UInt32;
namespace Community.CsharpSqlite
{
public partial class Sqlite3
{
/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
*************************************************************************
** Included in SQLite3 port to C#-SQLite; 2008 Noah B Hart
** C#-SQLite is an independent reimplementation of the SQLite software library
**
** SQLITE_SOURCE_ID: 2011-06-23 19:49:22 4374b7e83ea0a3fbc3691f9c0c936272862f32f2
**
*************************************************************************
*/
//#include "sqliteInt.h"
/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
*/
static void clearSelect( sqlite3 db, Select p )
{
sqlite3ExprListDelete( db, ref p.pEList );
sqlite3SrcListDelete( db, ref p.pSrc );
sqlite3ExprDelete( db, ref p.pWhere );
sqlite3ExprListDelete( db, ref p.pGroupBy );
sqlite3ExprDelete( db, ref p.pHaving );
sqlite3ExprListDelete( db, ref p.pOrderBy );
sqlite3SelectDelete( db, ref p.pPrior );
sqlite3ExprDelete( db, ref p.pLimit );
sqlite3ExprDelete( db, ref p.pOffset );
}
/*
** Initialize a SelectDest structure.
*/
static void sqlite3SelectDestInit( SelectDest pDest, int eDest, int iParm )
{
pDest.eDest = (u8)eDest;
pDest.iParm = iParm;
pDest.affinity = '\0';
pDest.iMem = 0;
pDest.nMem = 0;
}
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
// OVERLOADS, so I don't need to rewrite parse.c
static Select sqlite3SelectNew( Parse pParse, int null_2, SrcList pSrc, int null_4, int null_5, int null_6, int null_7, int isDistinct, int null_9, int null_10 )
{
return sqlite3SelectNew( pParse, null, pSrc, null, null, null, null, isDistinct, null, null );
}
static Select sqlite3SelectNew(
Parse pParse, /* Parsing context */
ExprList pEList, /* which columns to include in the result */
SrcList pSrc, /* the FROM clause -- which tables to scan */
Expr pWhere, /* the WHERE clause */
ExprList pGroupBy, /* the GROUP BY clause */
Expr pHaving, /* the HAVING clause */
ExprList pOrderBy, /* the ORDER BY clause */
int isDistinct, /* true if the DISTINCT keyword is present */
Expr pLimit, /* LIMIT value. NULL means not used */
Expr pOffset /* OFFSET value. NULL means no offset */
)
{
Select pNew;
// Select standin;
sqlite3 db = pParse.db;
pNew = new Select();//sqlite3DbMallocZero(db, sizeof(*pNew) );
Debug.Assert( //db.mallocFailed != 0 ||
null == pOffset || pLimit != null ); /* OFFSET implies LIMIT */
//if( pNew==null ){
// pNew = standin;
// memset(pNew, 0, sizeof(*pNew));
//}
if ( pEList == null )
{
pEList = sqlite3ExprListAppend( pParse, null, sqlite3Expr( db, TK_ALL, null ) );
}
pNew.pEList = pEList;
pNew.pSrc = pSrc;
pNew.pWhere = pWhere;
pNew.pGroupBy = pGroupBy;
pNew.pHaving = pHaving;
pNew.pOrderBy = pOrderBy;
pNew.selFlags = (u16)( isDistinct != 0 ? SF_Distinct : 0 );
pNew.op = TK_SELECT;
pNew.pLimit = pLimit;
pNew.pOffset = pOffset;
Debug.Assert( pOffset == null || pLimit != null );
pNew.addrOpenEphm[0] = -1;
pNew.addrOpenEphm[1] = -1;
pNew.addrOpenEphm[2] = -1;
//if ( db.mallocFailed != 0 )
//{
// clearSelect( db, pNew );
// //if ( pNew != standin ) sqlite3DbFree( db, ref pNew );
// pNew = null;
//}
return pNew;
}
/*
** Delete the given Select structure and all of its substructures.
*/
static void sqlite3SelectDelete( sqlite3 db, ref Select p )
{
if ( p != null )
{
clearSelect( db, p );
sqlite3DbFree( db, ref p );
}
}
/*
** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
** type of join. Return an integer constant that expresses that type
** in terms of the following bit values:
**
** JT_INNER
** JT_CROSS
** JT_OUTER
** JT_NATURAL
** JT_LEFT
** JT_RIGHT
**
** A full outer join is the combination of JT_LEFT and JT_RIGHT.
**
** If an illegal or unsupported join type is seen, then still return
** a join type, but put an error in the pParse structure.
*/
class Keyword
{
public u8 i; /* Beginning of keyword text in zKeyText[] */
public u8 nChar; /* Length of the keyword in characters */
public u8 code; /* Join type mask */
public Keyword( u8 i, u8 nChar, u8 code )
{
this.i = i;
this.nChar = nChar;
this.code = code;
}
}
// OVERLOADS, so I don't need to rewrite parse.c
static int sqlite3JoinType( Parse pParse, Token pA, int null_3, int null_4 )
{
return sqlite3JoinType( pParse, pA, null, null );
}
static int sqlite3JoinType( Parse pParse, Token pA, Token pB, int null_4 )
{
return sqlite3JoinType( pParse, pA, pB, null );
}
static int sqlite3JoinType( Parse pParse, Token pA, Token pB, Token pC )
{
int jointype = 0;
Token[] apAll = new Token[3];
Token p;
/* 0123456789 123456789 123456789 123 */
string zKeyText = "naturaleftouterightfullinnercross";
Keyword[] aKeyword = new Keyword[]{
/* natural */ new Keyword( 0, 7, JT_NATURAL ),
/* left */ new Keyword( 6, 4, JT_LEFT|JT_OUTER ),
/* outer */ new Keyword( 10, 5, JT_OUTER ),
/* right */ new Keyword( 14, 5, JT_RIGHT|JT_OUTER ),
/* full */ new Keyword( 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER ),
/* inner */ new Keyword( 23, 5, JT_INNER ),
/* cross */ new Keyword( 28, 5, JT_INNER|JT_CROSS ),
};
int i, j;
apAll[0] = pA;
apAll[1] = pB;
apAll[2] = pC;
for ( i = 0; i < 3 && apAll[i] != null; i++ )
{
p = apAll[i];
for ( j = 0; j < ArraySize( aKeyword ); j++ )
{
if ( p.n == aKeyword[j].nChar
&& p.z.StartsWith( zKeyText.Substring( aKeyword[j].i, aKeyword[j].nChar ), StringComparison.OrdinalIgnoreCase ) )
{
jointype |= aKeyword[j].code;
break;
}
}
testcase( j == 0 || j == 1 || j == 2 || j == 3 || j == 4 || j == 5 || j == 6 );
if ( j >= ArraySize( aKeyword ) )
{
jointype |= JT_ERROR;
break;
}
}
if (
( jointype & ( JT_INNER | JT_OUTER ) ) == ( JT_INNER | JT_OUTER ) ||
( jointype & JT_ERROR ) != 0
)
{
string zSp = pC == null ? string.Empty : " ";
Debug.Assert( pB != null );
sqlite3ErrorMsg( pParse, "unknown or unsupported join type: " +
"%T %T%s%T", pA, pB, zSp, pC );
jointype = JT_INNER;
}
else if ( ( jointype & JT_OUTER ) != 0
&& ( jointype & ( JT_LEFT | JT_RIGHT ) ) != JT_LEFT )
{
sqlite3ErrorMsg( pParse,
"RIGHT and FULL OUTER JOINs are not currently supported" );
jointype = JT_INNER;
}
return jointype;
}
/*
** Return the index of a column in a table. Return -1 if the column
** is not contained in the table.
*/
static int columnIndex( Table pTab, string zCol )
{
int i;
for ( i = 0; i < pTab.nCol; i++ )
{
if ( pTab.aCol[i].zName.Equals( zCol, StringComparison.OrdinalIgnoreCase ) )
return i;
}
return -1;
}
/*
** Search the first N tables in pSrc, from left to right, looking for a
** table that has a column named zCol.
**
** When found, set *piTab and *piCol to the table index and column index
** of the matching column and return TRUE.
**
** If not found, return FALSE.
*/
static int tableAndColumnIndex(
SrcList pSrc, /* Array of tables to search */
int N, /* Number of tables in pSrc.a[] to search */
string zCol, /* Name of the column we are looking for */
ref int piTab, /* Write index of pSrc.a[] here */
ref int piCol /* Write index of pSrc.a[*piTab].pTab.aCol[] here */
)
{
int i; /* For looping over tables in pSrc */
int iCol; /* Index of column matching zCol */
Debug.Assert( ( piTab == 0 ) == ( piCol == 0 ) ); /* Both or neither are NULL */
for ( i = 0; i < N; i++ )
{
iCol = columnIndex( pSrc.a[i].pTab, zCol );
if ( iCol >= 0 )
{
//if( piTab )
{
piTab = i;
piCol = iCol;
}
return 1;
}
}
return 0;
}
/*
** This function is used to add terms implied by JOIN syntax to the
** WHERE clause expression of a SELECT statement. The new term, which
** is ANDed with the existing WHERE clause, is of the form:
**
** (vtab1.col1 = tab2.col2)
**
** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the
** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is
** column iColRight of tab2.
*/
static void addWhereTerm(
Parse pParse, /* Parsing context */
SrcList pSrc, /* List of tables in FROM clause */
int iLeft, /* Index of first table to join in pSrc */
int iColLeft, /* Index of column in first table */
int iRight, /* Index of second table in pSrc */
int iColRight, /* Index of column in second table */
int isOuterJoin, /* True if this is an OUTER join */
ref Expr ppWhere /* IN/OUT: The WHERE clause to add to */
)
{
sqlite3 db = pParse.db;
Expr pE1;
Expr pE2;
Expr pEq;
Debug.Assert( iLeft < iRight );
Debug.Assert( pSrc.nSrc > iRight );
Debug.Assert( pSrc.a[iLeft].pTab != null );
Debug.Assert( pSrc.a[iRight].pTab != null );
pE1 = sqlite3CreateColumnExpr( db, pSrc, iLeft, iColLeft );
pE2 = sqlite3CreateColumnExpr( db, pSrc, iRight, iColRight );
pEq = sqlite3PExpr( pParse, TK_EQ, pE1, pE2, 0 );
if ( pEq != null && isOuterJoin != 0 )
{
ExprSetProperty( pEq, EP_FromJoin );
Debug.Assert( !ExprHasAnyProperty( pEq, EP_TokenOnly | EP_Reduced ) );
ExprSetIrreducible( pEq );
pEq.iRightJoinTable = (i16)pE2.iTable;
}
ppWhere = sqlite3ExprAnd( db, ppWhere, pEq );
}
/*
** Set the EP_FromJoin property on all terms of the given expression.
** And set the Expr.iRightJoinTable to iTable for every term in the
** expression.
**
** The EP_FromJoin property is used on terms of an expression to tell
** the LEFT OUTER JOIN processing logic that this term is part of the
** join restriction specified in the ON or USING clause and not a part
** of the more general WHERE clause. These terms are moved over to the
** WHERE clause during join processing but we need to remember that they
** originated in the ON or USING clause.
**
** The Expr.iRightJoinTable tells the WHERE clause processing that the
** expression depends on table iRightJoinTable even if that table is not
** explicitly mentioned in the expression. That information is needed
** for cases like this:
**
** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
**
** The where clause needs to defer the handling of the t1.x=5
** term until after the t2 loop of the join. In that way, a
** NULL t2 row will be inserted whenever t1.x!=5. If we do not
** defer the handling of t1.x=5, it will be processed immediately
** after the t1 loop and rows with t1.x!=5 will never appear in
** the output, which is incorrect.
*/
static void setJoinExpr( Expr p, int iTable )
{
while ( p != null )
{
ExprSetProperty( p, EP_FromJoin );
Debug.Assert( !ExprHasAnyProperty( p, EP_TokenOnly | EP_Reduced ) );
ExprSetIrreducible( p );
p.iRightJoinTable = (i16)iTable;
setJoinExpr( p.pLeft, iTable );
p = p.pRight;
}
}
/*
** This routine processes the join information for a SELECT statement.
** ON and USING clauses are converted into extra terms of the WHERE clause.
** NATURAL joins also create extra WHERE clause terms.
**
** The terms of a FROM clause are contained in the Select.pSrc structure.
** The left most table is the first entry in Select.pSrc. The right-most
** table is the last entry. The join operator is held in the entry to
** the left. Thus entry 0 contains the join operator for the join between
** entries 0 and 1. Any ON or USING clauses associated with the join are
** also attached to the left entry.
**
** This routine returns the number of errors encountered.
*/
static int sqliteProcessJoin( Parse pParse, Select p )
{
SrcList pSrc; /* All tables in the FROM clause */
int i;
int j; /* Loop counters */
SrcList_item pLeft; /* Left table being joined */
SrcList_item pRight; /* Right table being joined */
pSrc = p.pSrc;
//pLeft = pSrc.a[0];
//pRight = pLeft[1];
for ( i = 0; i < pSrc.nSrc - 1; i++ )
{
pLeft = pSrc.a[i]; // pLeft ++
pRight = pSrc.a[i + 1];//Right++,
Table pLeftTab = pLeft.pTab;
Table pRightTab = pRight.pTab;
bool isOuter;
if ( NEVER( pLeftTab == null || pRightTab == null ) )
continue;
isOuter = ( pRight.jointype & JT_OUTER ) != 0;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if ( ( pRight.jointype & JT_NATURAL ) != 0 )
{
if ( pRight.pOn != null || pRight.pUsing != null )
{
sqlite3ErrorMsg( pParse, "a NATURAL join may not have " +
"an ON or USING clause", string.Empty );
return 1;
}
for ( j = 0; j < pRightTab.nCol; j++ )
{
string zName; /* Name of column in the right table */
int iLeft = 0; /* Matching left table */
int iLeftCol = 0; /* Matching column in the left table */
zName = pRightTab.aCol[j].zName;
////int iRightCol = columnIndex( pRightTab, zName );
if ( tableAndColumnIndex( pSrc, i + 1, zName, ref iLeft, ref iLeftCol ) != 0 )
{
addWhereTerm( pParse, pSrc, iLeft, iLeftCol, i + 1, j,
isOuter ? 1 : 0, ref p.pWhere );
}
}
}
/* Disallow both ON and USING clauses in the same join
*/
if ( pRight.pOn != null && pRight.pUsing != null )
{
sqlite3ErrorMsg( pParse, "cannot have both ON and USING " +
"clauses in the same join" );
return 1;
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
if ( pRight.pOn != null )
{
if ( isOuter )
setJoinExpr( pRight.pOn, pRight.iCursor );
p.pWhere = sqlite3ExprAnd( pParse.db, p.pWhere, pRight.pOn );
pRight.pOn = null;
}
/* Create extra terms on the WHERE clause for each column named
** in the USING clause. Example: If the two tables to be joined are
** A and B and the USING clause names X, Y, and Z, then add this
** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
** Report an error if any column mentioned in the USING clause is
** not contained in both tables to be joined.
*/
if ( pRight.pUsing != null )
{
IdList pList = pRight.pUsing;
for ( j = 0; j < pList.nId; j++ )
{
string zName; /* Name of the term in the USING clause */
int iLeft = 0; /* Table on the left with matching column name */
int iLeftCol = 0; /* Column number of matching column on the left */
int iRightCol; /* Column number of matching column on the right */
zName = pList.a[j].zName;
iRightCol = columnIndex( pRightTab, zName );
if ( iRightCol < 0
|| 0 == tableAndColumnIndex( pSrc, i + 1, zName, ref iLeft, ref iLeftCol )
)
{
sqlite3ErrorMsg( pParse, "cannot join using column %s - column " +
"not present in both tables", zName );
return 1;
}
addWhereTerm( pParse, pSrc, iLeft, iLeftCol, i + 1, iRightCol,
isOuter ? 1 : 0, ref p.pWhere );
}
}
}
return 0;
}
/*
** Insert code into "v" that will push the record on the top of the
** stack into the sorter.
*/
static void pushOntoSorter(
Parse pParse, /* Parser context */
ExprList pOrderBy, /* The ORDER BY clause */
Select pSelect, /* The whole SELECT statement */
int regData /* Register holding data to be sorted */
)
{
Vdbe v = pParse.pVdbe;
int nExpr = pOrderBy.nExpr;
int regBase = sqlite3GetTempRange( pParse, nExpr + 2 );
int regRecord = sqlite3GetTempReg( pParse );
sqlite3ExprCacheClear( pParse );
sqlite3ExprCodeExprList( pParse, pOrderBy, regBase, false );
sqlite3VdbeAddOp2( v, OP_Sequence, pOrderBy.iECursor, regBase + nExpr );
sqlite3ExprCodeMove( pParse, regData, regBase + nExpr + 1, 1 );
sqlite3VdbeAddOp3( v, OP_MakeRecord, regBase, nExpr + 2, regRecord );
sqlite3VdbeAddOp2( v, OP_IdxInsert, pOrderBy.iECursor, regRecord );
sqlite3ReleaseTempReg( pParse, regRecord );
sqlite3ReleaseTempRange( pParse, regBase, nExpr + 2 );
if ( pSelect.iLimit != 0 )
{
int addr1, addr2;
int iLimit;
if ( pSelect.iOffset != 0 )
{
iLimit = pSelect.iOffset + 1;
}
else
{
iLimit = pSelect.iLimit;
}
addr1 = sqlite3VdbeAddOp1( v, OP_IfZero, iLimit );
sqlite3VdbeAddOp2( v, OP_AddImm, iLimit, -1 );
addr2 = sqlite3VdbeAddOp0( v, OP_Goto );
sqlite3VdbeJumpHere( v, addr1 );
sqlite3VdbeAddOp1( v, OP_Last, pOrderBy.iECursor );
sqlite3VdbeAddOp1( v, OP_Delete, pOrderBy.iECursor );
sqlite3VdbeJumpHere( v, addr2 );
}
}
/*
** Add code to implement the OFFSET
*/
static void codeOffset(
Vdbe v, /* Generate code into this VM */
Select p, /* The SELECT statement being coded */
int iContinue /* Jump here to skip the current record */
)
{
if ( p.iOffset != 0 && iContinue != 0 )
{
int addr;
sqlite3VdbeAddOp2( v, OP_AddImm, p.iOffset, -1 );
addr = sqlite3VdbeAddOp1( v, OP_IfNeg, p.iOffset );
sqlite3VdbeAddOp2( v, OP_Goto, 0, iContinue );
#if SQLITE_DEBUG
VdbeComment( v, "skip OFFSET records" );
#endif
sqlite3VdbeJumpHere( v, addr );
}
}
/*
** Add code that will check to make sure the N registers starting at iMem
** form a distinct entry. iTab is a sorting index that holds previously
** seen combinations of the N values. A new entry is made in iTab
** if the current N values are new.
**
** A jump to addrRepeat is made and the N+1 values are popped from the
** stack if the top N elements are not distinct.
*/
static void codeDistinct(
Parse pParse, /* Parsing and code generating context */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
int N, /* Number of elements */
int iMem /* First element */
)
{
Vdbe v;
int r1;
v = pParse.pVdbe;
r1 = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp4Int( v, OP_Found, iTab, addrRepeat, iMem, N );
sqlite3VdbeAddOp3( v, OP_MakeRecord, iMem, N, r1 );
sqlite3VdbeAddOp2( v, OP_IdxInsert, iTab, r1 );
sqlite3ReleaseTempReg( pParse, r1 );
}
#if !SQLITE_OMIT_SUBQUERY
/*
** Generate an error message when a SELECT is used within a subexpression
** (example: "a IN (SELECT * FROM table)") but it has more than 1 result
** column. We do this in a subroutine because the error used to occur
** in multiple places. (The error only occurs in one place now, but we
** retain the subroutine to minimize code disruption.)
*/
static bool checkForMultiColumnSelectError(
Parse pParse, /* Parse context. */
SelectDest pDest, /* Destination of SELECT results */
int nExpr /* Number of result columns returned by SELECT */
)
{
int eDest = pDest.eDest;
if ( nExpr > 1 && ( eDest == SRT_Mem || eDest == SRT_Set ) )
{
sqlite3ErrorMsg( pParse, "only a single result allowed for " +
"a SELECT that is part of an expression" );
return true;
}
else
{
return false;
}
}
#endif
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab and nColumn are both zero, then the pEList expressions
** are evaluated in order to get the data for this row. If nColumn>0
** then data is pulled from srcTab and pEList is used only to get the
** datatypes for each column.
*/
static void selectInnerLoop(
Parse pParse, /* The parser context */
Select p, /* The complete select statement being coded */
ExprList pEList, /* List of values being extracted */
int srcTab, /* Pull data from this table */
int nColumn, /* Number of columns in the source table */
ExprList pOrderBy, /* If not NULL, sort results using this key */
int distinct, /* If >=0, make sure results are distinct */
SelectDest pDest, /* How to dispose of the results */
int iContinue, /* Jump here to continue with next row */
int iBreak /* Jump here to break out of the inner loop */
)
{
Vdbe v = pParse.pVdbe;
int i;
bool hasDistinct; /* True if the DISTINCT keyword is present */
int regResult; /* Start of memory holding result set */
int eDest = pDest.eDest; /* How to dispose of results */
int iParm = pDest.iParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
Debug.Assert( v != null );
if ( NEVER( v == null ) )
return;
Debug.Assert( pEList != null );
hasDistinct = distinct >= 0;
if ( pOrderBy == null && !hasDistinct )
{
codeOffset( v, p, iContinue );
}
/* Pull the requested columns.
*/
if ( nColumn > 0 )
{
nResultCol = nColumn;
}
else
{
nResultCol = pEList.nExpr;
}
if ( pDest.iMem == 0 )
{
pDest.iMem = pParse.nMem + 1;
pDest.nMem = nResultCol;
pParse.nMem += nResultCol;
}
else
{
Debug.Assert( pDest.nMem == nResultCol );
}
regResult = pDest.iMem;
if ( nColumn > 0 )
{
for ( i = 0; i < nColumn; i++ )
{
sqlite3VdbeAddOp3( v, OP_Column, srcTab, i, regResult + i );
}
}
else if ( eDest != SRT_Exists )
{
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
sqlite3ExprCacheClear( pParse );
sqlite3ExprCodeExprList( pParse, pEList, regResult, eDest == SRT_Output );
}
nColumn = nResultCol;
/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
** part of the result.
*/
if ( hasDistinct )
{
Debug.Assert( pEList != null );
Debug.Assert( pEList.nExpr == nColumn );
codeDistinct( pParse, distinct, iContinue, nColumn, regResult );
if ( pOrderBy == null )
{
codeOffset( v, p, iContinue );
}
}
switch ( eDest )
{
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
#if !SQLITE_OMIT_COMPOUND_SELECT
case SRT_Union:
{
int r1;
r1 = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp3( v, OP_MakeRecord, regResult, nColumn, r1 );
sqlite3VdbeAddOp2( v, OP_IdxInsert, iParm, r1 );
sqlite3ReleaseTempReg( pParse, r1 );
break;
}
/* Construct a record from the query result, but instead of
** saving that record, use it as a key to delete elements from
** the temporary table iParm.
*/
case SRT_Except:
{
sqlite3VdbeAddOp3( v, OP_IdxDelete, iParm, regResult, nColumn );
break;
}
#endif
/* Store the result as data using a unique key.
*/
case SRT_Table:
case SRT_EphemTab:
{
int r1 = sqlite3GetTempReg( pParse );
testcase( eDest == SRT_Table );
testcase( eDest == SRT_EphemTab );
sqlite3VdbeAddOp3( v, OP_MakeRecord, regResult, nColumn, r1 );
if ( pOrderBy != null )
{
pushOntoSorter( pParse, pOrderBy, p, r1 );
}
else
{
int r2 = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp2( v, OP_NewRowid, iParm, r2 );
sqlite3VdbeAddOp3( v, OP_Insert, iParm, r1, r2 );
sqlite3VdbeChangeP5( v, OPFLAG_APPEND );
sqlite3ReleaseTempReg( pParse, r2 );
}
sqlite3ReleaseTempReg( pParse, r1 );
break;
}
#if !SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)" construct,
** then there should be a single item on the stack. Write this
** item into the set table with bogus data.
*/
case SRT_Set:
{
Debug.Assert( nColumn == 1 );
p.affinity = sqlite3CompareAffinity( pEList.a[0].pExpr, pDest.affinity );
if ( pOrderBy != null )
{
/* At first glance you would think we could optimize out the
** ORDER BY in this case since the order of entries in the set
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter( pParse, pOrderBy, p, regResult );
}
else
{
int r1 = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp4( v, OP_MakeRecord, regResult, 1, r1, p.affinity, 1 );
sqlite3ExprCacheAffinityChange( pParse, regResult, 1 );
sqlite3VdbeAddOp2( v, OP_IdxInsert, iParm, r1 );
sqlite3ReleaseTempReg( pParse, r1 );
}
break;
}
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists:
{
sqlite3VdbeAddOp2( v, OP_Integer, 1, iParm );
/* The LIMIT clause will terminate the loop for us */
break;
}
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell and break out
** of the scan loop.
*/
case SRT_Mem:
{
Debug.Assert( nColumn == 1 );
if ( pOrderBy != null )
{
pushOntoSorter( pParse, pOrderBy, p, regResult );
}
else
{
sqlite3ExprCodeMove( pParse, regResult, iParm, 1 );
/* The LIMIT clause will jump out of the loop for us */
}
break;
}
#endif // * #if !SQLITE_OMIT_SUBQUERY */
/* Send the data to the callback function or to a subroutine. In the
** case of a subroutine, the subroutine itself is responsible for
** popping the data from the stack.
*/
case SRT_Coroutine:
case SRT_Output:
{
testcase( eDest == SRT_Coroutine );
testcase( eDest == SRT_Output );
if ( pOrderBy != null )
{
int r1 = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp3( v, OP_MakeRecord, regResult, nColumn, r1 );
pushOntoSorter( pParse, pOrderBy, p, r1 );
sqlite3ReleaseTempReg( pParse, r1 );
}
else if ( eDest == SRT_Coroutine )
{
sqlite3VdbeAddOp1( v, OP_Yield, pDest.iParm );
}
else
{
sqlite3VdbeAddOp2( v, OP_ResultRow, regResult, nColumn );
sqlite3ExprCacheAffinityChange( pParse, regResult, nColumn );
}
break;
}
#if !SQLITE_OMIT_TRIGGER
/* Discard the results. This is used for SELECT statements inside
** the body of a TRIGGER. The purpose of such selects is to call
** user-defined functions that have side effects. We do not care
** about the actual results of the select.
*/
default:
{
Debug.Assert( eDest == SRT_Discard );
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached. Except, if
** there is a sorter, in which case the sorter has already limited
** the output for us.
*/
if ( pOrderBy == null && p.iLimit != 0 )
{
sqlite3VdbeAddOp3( v, OP_IfZero, p.iLimit, iBreak, -1 );
}
}
/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.
**
** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
** KeyInfo structure is appropriate for initializing a virtual index to
** implement that clause. If the ExprList is the result set of a SELECT
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc. The calling
** function is responsible for seeing that this structure is eventually
** freed. Add the KeyInfo structure to the P4 field of an opcode using
** P4_KEYINFO_HANDOFF is the usual way of dealing with this.
*/
static KeyInfo keyInfoFromExprList( Parse pParse, ExprList pList )
{
sqlite3 db = pParse.db;
int nExpr;
KeyInfo pInfo;
ExprList_item pItem;
int i;
nExpr = pList.nExpr;
pInfo = new KeyInfo();//sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(CollSeq*.Length+1) );
if ( pInfo != null )
{
pInfo.aSortOrder = new byte[nExpr];// pInfo.aColl[nExpr];
pInfo.aColl = new CollSeq[nExpr];
pInfo.nField = (u16)nExpr;
pInfo.enc = db.aDbStatic[0].pSchema.enc;// ENC(db);
pInfo.db = db;
for ( i = 0; i < nExpr; i++ )
{//, pItem++){
pItem = pList.a[i];
CollSeq pColl;
pColl = sqlite3ExprCollSeq( pParse, pItem.pExpr );
if ( pColl == null )
{
pColl = db.pDfltColl;
}
pInfo.aColl[i] = pColl;
pInfo.aSortOrder[i] = (byte)pItem.sortOrder;
}
}
return pInfo;
}
#if !SQLITE_OMIT_COMPOUND_SELECT
/*
** Name of the connection operator, used for error messages.
*/
static string selectOpName( int id )
{
string z;
switch ( id )
{
case TK_ALL:
z = "UNION ALL";
break;
case TK_INTERSECT:
z = "INTERSECT";
break;
case TK_EXCEPT:
z = "EXCEPT";
break;
default:
z = "UNION";
break;
}
return z;
}
#endif //* SQLITE_OMIT_COMPOUND_SELECT */
#if !SQLITE_OMIT_EXPLAIN
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of the form:
**
** "USE TEMP B-TREE FOR xxx"
**
** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which
** is determined by the zUsage argument.
*/
static void explainTempTable( Parse pParse, string zUsage )
{
if ( pParse.explain == 2 )
{
Vdbe v = pParse.pVdbe;
string zMsg = sqlite3MPrintf( pParse.db, "USE TEMP B-TREE FOR %s", zUsage );
sqlite3VdbeAddOp4( v, OP_Explain, pParse.iSelectId, 0, 0, zMsg, P4_DYNAMIC );
}
}
/*
** Assign expression b to lvalue a. A second, no-op, version of this macro
** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
** in sqlite3Select() to assign values to structure member variables that
** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the
** code with #if !directives.
*/
//# define explainSetInteger(a, b) a = b
static void explainSetInteger( ref int a, int b )
{
a = b;
}
static void explainSetInteger( ref byte a, int b )
{
a = (byte)b;
}
#else
/* No-op versions of the explainXXX() functions and macros. */
//# define explainTempTable(y,z)
static void explainTempTable(ref int a, int b){ a = b;}
//# define explainSetInteger(y,z)
static void explainSetInteger(ref int a, int b){ a = b;}
#endif
#if !(SQLITE_OMIT_EXPLAIN) && !(SQLITE_OMIT_COMPOUND_SELECT)
/*
** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
** is a no-op. Otherwise, it adds a single row of output to the EQP result,
** where the caption is of one of the two forms:
**
** "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)"
** "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)"
**
** where iSub1 and iSub2 are the integers passed as the corresponding
** function parameters, and op is the text representation of the parameter
** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT,
** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is
** false, or the second form if it is true.
*/
static void explainComposite(
Parse pParse, /* Parse context */
int op, /* One of TK_UNION, TK_EXCEPT etc. */
int iSub1, /* Subquery id 1 */
int iSub2, /* Subquery id 2 */
bool bUseTmp /* True if a temp table was used */
)
{
Debug.Assert( op == TK_UNION || op == TK_EXCEPT || op == TK_INTERSECT || op == TK_ALL );
if ( pParse.explain == 2 )
{
Vdbe v = pParse.pVdbe;
string zMsg = sqlite3MPrintf(
pParse.db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2,
bUseTmp ? "USING TEMP B-TREE " : string.Empty, selectOpName( op )
);
sqlite3VdbeAddOp4( v, OP_Explain, pParse.iSelectId, 0, 0, zMsg, P4_DYNAMIC );
}
}
#else
/* No-op versions of the explainXXX() functions and macros. */
//# define explainComposite(v,w,x,y,z)
static void explainComposite(Parse v, int w,int x,int y,bool z) {}
#endif
/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter. After the loop is terminated
** we need to run the sorter and output the results. The following
** routine generates the code needed to do that.
*/
static void generateSortTail(
Parse pParse, /* Parsing context */
Select p, /* The SELECT statement */
Vdbe v, /* Generate code into this VDBE */
int nColumn, /* Number of columns of data */
SelectDest pDest /* Write the sorted results here */
)
{
int addrBreak = sqlite3VdbeMakeLabel( v ); /* Jump here to exit loop */
int addrContinue = sqlite3VdbeMakeLabel( v ); /* Jump here for next cycle */
int addr;
int iTab;
int pseudoTab = 0;
ExprList pOrderBy = p.pOrderBy;
int eDest = pDest.eDest;
int iParm = pDest.iParm;
int regRow;
int regRowid;
iTab = pOrderBy.iECursor;
regRow = sqlite3GetTempReg( pParse );
if ( eDest == SRT_Output || eDest == SRT_Coroutine )
{
pseudoTab = pParse.nTab++;
sqlite3VdbeAddOp3( v, OP_OpenPseudo, pseudoTab, regRow, nColumn );
regRowid = 0;
}
else
{
regRowid = sqlite3GetTempReg( pParse );
}
addr = 1 + sqlite3VdbeAddOp2( v, OP_Sort, iTab, addrBreak );
codeOffset( v, p, addrContinue );
sqlite3VdbeAddOp3( v, OP_Column, iTab, pOrderBy.nExpr + 1, regRow );
switch ( eDest )
{
case SRT_Table:
case SRT_EphemTab:
{
testcase( eDest == SRT_Table );
testcase( eDest == SRT_EphemTab );
sqlite3VdbeAddOp2( v, OP_NewRowid, iParm, regRowid );
sqlite3VdbeAddOp3( v, OP_Insert, iParm, regRow, regRowid );
sqlite3VdbeChangeP5( v, OPFLAG_APPEND );
break;
}
#if !SQLITE_OMIT_SUBQUERY
case SRT_Set:
{
Debug.Assert( nColumn == 1 );
sqlite3VdbeAddOp4( v, OP_MakeRecord, regRow, 1, regRowid, p.affinity, 1 );
sqlite3ExprCacheAffinityChange( pParse, regRow, 1 );
sqlite3VdbeAddOp2( v, OP_IdxInsert, iParm, regRowid );
break;
}
case SRT_Mem:
{
Debug.Assert( nColumn == 1 );
sqlite3ExprCodeMove( pParse, regRow, iParm, 1 );
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
default:
{
int i;
Debug.Assert( eDest == SRT_Output || eDest == SRT_Coroutine );
testcase( eDest == SRT_Output );
testcase( eDest == SRT_Coroutine );
for ( i = 0; i < nColumn; i++ )
{
Debug.Assert( regRow != pDest.iMem + i );
sqlite3VdbeAddOp3( v, OP_Column, pseudoTab, i, pDest.iMem + i );
if ( i == 0 )
{
sqlite3VdbeChangeP5( v, OPFLAG_CLEARCACHE );
}
}
if ( eDest == SRT_Output )
{
sqlite3VdbeAddOp2( v, OP_ResultRow, pDest.iMem, nColumn );
sqlite3ExprCacheAffinityChange( pParse, pDest.iMem, nColumn );
}
else
{
sqlite3VdbeAddOp1( v, OP_Yield, pDest.iParm );
}
break;
}
}
sqlite3ReleaseTempReg( pParse, regRow );
sqlite3ReleaseTempReg( pParse, regRowid );
/* The bottom of the loop
*/
sqlite3VdbeResolveLabel( v, addrContinue );
sqlite3VdbeAddOp2( v, OP_Next, iTab, addr );
sqlite3VdbeResolveLabel( v, addrBreak );
if ( eDest == SRT_Output || eDest == SRT_Coroutine )
{
sqlite3VdbeAddOp2( v, OP_Close, pseudoTab, 0 );
}
}
/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** The declaration type is the exact datatype definition extracted from the
** original CREATE TABLE statement if the expression is a column. The
** declaration type for a ROWID field is INTEGER. Exactly when an expression
** is considered a column can be complex in the presence of subqueries. The
** result-set expression in all of the following SELECT statements is
** considered a column by this function.
**
** SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl);
** SELECT abc FROM (SELECT col AS abc FROM tbl);
**
** The declaration type for any expression other than a column is NULL.
*/
static string columnType(
NameContext pNC,
Expr pExpr,
ref string pzOriginDb,
ref string pzOriginTab,
ref string pzOriginCol
)
{
string zType = null;
string zOriginDb = null;
string zOriginTab = null;
string zOriginCol = null;
int j;
if ( NEVER( pExpr == null ) || pNC.pSrcList == null )
return null;
switch ( pExpr.op )
{
case TK_AGG_COLUMN:
case TK_COLUMN:
{
/* The expression is a column. Locate the table the column is being
** extracted from in NameContext.pSrcList. This table may be real
** database table or a subquery.
*/
Table pTab = null; /* Table structure column is extracted from */
Select pS = null; /* Select the column is extracted from */
int iCol = pExpr.iColumn; /* Index of column in pTab */
testcase( pExpr.op == TK_AGG_COLUMN );
testcase( pExpr.op == TK_COLUMN );
while ( pNC != null && pTab == null )
{
SrcList pTabList = pNC.pSrcList;
for ( j = 0; j < pTabList.nSrc && pTabList.a[j].iCursor != pExpr.iTable; j++ )
;
if ( j < pTabList.nSrc )
{
pTab = pTabList.a[j].pTab;
pS = pTabList.a[j].pSelect;
}
else
{
pNC = pNC.pNext;
}
}
if ( pTab == null )
{
/* At one time, code such as "SELECT new.x" within a trigger would
** cause this condition to run. Since then, we have restructured how
** trigger code is generated and so this condition is no longer
** possible. However, it can still be true for statements like
** the following:
**
** CREATE TABLE t1(col INTEGER);
** SELECT (SELECT t1.col) FROM FROM t1;
**
** when columnType() is called on the expression "t1.col" in the
** sub-select. In this case, set the column type to NULL, even
** though it should really be "INTEGER".
**
** This is not a problem, as the column type of "t1.col" is never
** used. When columnType() is called on the expression
** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT
** branch below. */
break;
}
//Debug.Assert( pTab != null && pExpr.pTab == pTab );
if ( pS != null )
{
/* The "table" is actually a sub-select or a view in the FROM clause
** of the SELECT statement. Return the declaration type and origin
** data for the result-set column of the sub-select.
*/
if ( iCol >= 0 && ALWAYS( iCol < pS.pEList.nExpr ) )
{
/* If iCol is less than zero, then the expression requests the
** rowid of the sub-select or view. This expression is legal (see
** test case misc2.2.2) - it always evaluates to NULL.
*/
NameContext sNC = new NameContext();
Expr p = pS.pEList.a[iCol].pExpr;
sNC.pSrcList = pS.pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC.pParse;
zType = columnType( sNC, p, ref zOriginDb, ref zOriginTab, ref zOriginCol );
}
}
else if ( ALWAYS( pTab.pSchema ) )
{
/* A real table */
Debug.Assert( pS == null );
if ( iCol < 0 )
iCol = pTab.iPKey;
Debug.Assert( iCol == -1 || ( iCol >= 0 && iCol < pTab.nCol ) );
if ( iCol < 0 )
{
zType = "INTEGER";
zOriginCol = "rowid";
}
else
{
zType = pTab.aCol[iCol].zType;
zOriginCol = pTab.aCol[iCol].zName;
}
zOriginTab = pTab.zName;
if ( pNC.pParse != null )
{
int iDb = sqlite3SchemaToIndex( pNC.pParse.db, pTab.pSchema );
zOriginDb = pNC.pParse.db.aDb[iDb].zName;
}
}
break;
}
#if !SQLITE_OMIT_SUBQUERY
case TK_SELECT:
{
/* The expression is a sub-select. Return the declaration type and
** origin info for the single column in the result set of the SELECT
** statement.
*/
NameContext sNC = new NameContext();
Select pS = pExpr.x.pSelect;
Expr p = pS.pEList.a[0].pExpr;
Debug.Assert( ExprHasProperty( pExpr, EP_xIsSelect ) );
sNC.pSrcList = pS.pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC.pParse;
zType = columnType( sNC, p, ref zOriginDb, ref zOriginTab, ref zOriginCol );
break;
}
#endif
}
//if ( pzOriginDb != null )
{
//Debug.Assert( pzOriginTab != null && pzOriginCol != null );
pzOriginDb = zOriginDb;
pzOriginTab = zOriginTab;
pzOriginCol = zOriginCol;
}
return zType;
}
/*
** Generate code that will tell the VDBE the declaration types of columns
** in the result set.
*/
static void generateColumnTypes(
Parse pParse, /* Parser context */
SrcList pTabList, /* List of tables */
ExprList pEList /* Expressions defining the result set */
)
{
#if !SQLITE_OMIT_DECLTYPE
Vdbe v = pParse.pVdbe;
int i;
NameContext sNC = new NameContext();
sNC.pSrcList = pTabList;
sNC.pParse = pParse;
for ( i = 0; i < pEList.nExpr; i++ )
{
Expr p = pEList.a[i].pExpr;
string zType;
#if SQLITE_ENABLE_COLUMN_METADATA
string zOrigDb = null;
string zOrigTab = null;
string zOrigCol = null;
zType = columnType( sNC, p, ref zOrigDb, ref zOrigTab, ref zOrigCol );
/* The vdbe must make its own copy of the column-type and other
** column specific strings, in case the schema is reset before this
** virtual machine is deleted.
*/
sqlite3VdbeSetColName( v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT );
sqlite3VdbeSetColName( v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT );
sqlite3VdbeSetColName( v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT );
#else
string sDummy = null;
zType = columnType( sNC, p, ref sDummy, ref sDummy, ref sDummy );
#endif
sqlite3VdbeSetColName( v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT );
}
#endif //* SQLITE_OMIT_DECLTYPE */
}
/*
** Generate code that will tell the VDBE the names of columns
** in the result set. This information is used to provide the
** azCol[] values in the callback.
*/
static void generateColumnNames(
Parse pParse, /* Parser context */
SrcList pTabList, /* List of tables */
ExprList pEList /* Expressions defining the result set */
)
{
Vdbe v = pParse.pVdbe;
int i, j;
sqlite3 db = pParse.db;
bool fullNames;
bool shortNames;
#if !SQLITE_OMIT_EXPLAIN
/* If this is an EXPLAIN, skip this step */
if ( pParse.explain != 0 )
{
return;
}
#endif
if ( pParse.colNamesSet != 0 || NEVER( v == null ) /*|| db.mallocFailed != 0 */ )
return;
pParse.colNamesSet = 1;
fullNames = ( db.flags & SQLITE_FullColNames ) != 0;
shortNames = ( db.flags & SQLITE_ShortColNames ) != 0;
sqlite3VdbeSetNumCols( v, pEList.nExpr );
for ( i = 0; i < pEList.nExpr; i++ )
{
Expr p;
p = pEList.a[i].pExpr;
if ( NEVER( p == null ) )
continue;
if ( pEList.a[i].zName != null )
{
string zName = pEList.a[i].zName;
sqlite3VdbeSetColName( v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT );
}
else if ( ( p.op == TK_COLUMN || p.op == TK_AGG_COLUMN ) && pTabList != null )
{
Table pTab;
string zCol;
int iCol = p.iColumn;
for ( j = 0; ALWAYS( j < pTabList.nSrc ); j++ )
{
if ( pTabList.a[j].iCursor == p.iTable )
break;
}
Debug.Assert( j < pTabList.nSrc );
pTab = pTabList.a[j].pTab;
if ( iCol < 0 )
iCol = pTab.iPKey;
Debug.Assert( iCol == -1 || ( iCol >= 0 && iCol < pTab.nCol ) );
if ( iCol < 0 )
{
zCol = "rowid";
}
else
{
zCol = pTab.aCol[iCol].zName;
}
if ( !shortNames && !fullNames )
{
sqlite3VdbeSetColName( v, i, COLNAME_NAME,
pEList.a[i].zSpan, SQLITE_DYNAMIC );//sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC);
}
else if ( fullNames )
{
string zName;
zName = sqlite3MPrintf( db, "%s.%s", pTab.zName, zCol );
sqlite3VdbeSetColName( v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC );
}
else
{
sqlite3VdbeSetColName( v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT );
}
}
else
{
sqlite3VdbeSetColName( v, i, COLNAME_NAME,
pEList.a[i].zSpan, SQLITE_DYNAMIC );//sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC);
}
}
generateColumnTypes( pParse, pTabList, pEList );
}
/*
** Given a an expression list (which is really the list of expressions
** that form the result set of a SELECT statement) compute appropriate
** column names for a table that would hold the expression list.
**
** All column names will be unique.
**
** Only the column names are computed. Column.zType, Column.zColl,
** and other fields of Column are zeroed.
**
** Return SQLITE_OK on success. If a memory allocation error occurs,
** store NULL in paCol and 0 in pnCol and return SQLITE_NOMEM.
*/
static int selectColumnsFromExprList(
Parse pParse, /* Parsing context */
ExprList pEList, /* Expr list from which to derive column names */
ref int pnCol, /* Write the number of columns here */
ref Column[] paCol /* Write the new column list here */
)
{
sqlite3 db = pParse.db; /* Database connection */
int i, j; /* Loop counters */
int cnt; /* Index added to make the name unique */
Column[] aCol;
Column pCol; /* For looping over result columns */
int nCol; /* Number of columns in the result set */
Expr p; /* Expression for a single result column */
string zName; /* Column name */
int nName; /* Size of name in zName[] */
pnCol = nCol = pEList.nExpr;
aCol = paCol = new Column[nCol];//sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
//if ( aCol == null )
// return SQLITE_NOMEM;
for ( i = 0; i < nCol; i++ )//, pCol++)
{
if ( aCol[i] == null )
aCol[i] = new Column();
pCol = aCol[i];
/* Get an appropriate name for the column
*/
p = pEList.a[i].pExpr;
Debug.Assert( p.pRight == null || ExprHasProperty( p.pRight, EP_IntValue )
|| p.pRight.u.zToken == null || p.pRight.u.zToken.Length > 0 );
if ( pEList.a[i].zName != null && ( zName = pEList.a[i].zName ) != string.Empty )
{
/* If the column contains an "AS <name>" phrase, use <name> as the name */
//zName = sqlite3DbStrDup(db, zName);
}
else
{
Expr pColExpr = p; /* The expression that is the result column name */
Table pTab; /* Table associated with this expression */
while ( pColExpr.op == TK_DOT )
pColExpr = pColExpr.pRight;
if ( pColExpr.op == TK_COLUMN && ALWAYS( pColExpr.pTab != null ) )
{
/* For columns use the column name name */
int iCol = pColExpr.iColumn;
pTab = pColExpr.pTab;
if ( iCol < 0 )
iCol = pTab.iPKey;
zName = sqlite3MPrintf( db, "%s",
iCol >= 0 ? pTab.aCol[iCol].zName : "rowid" );
}
else if ( pColExpr.op == TK_ID )
{
Debug.Assert( !ExprHasProperty( pColExpr, EP_IntValue ) );
zName = sqlite3MPrintf( db, "%s", pColExpr.u.zToken );
}
else
{
/* Use the original text of the column expression as its name */
zName = sqlite3MPrintf( db, "%s", pEList.a[i].zSpan );
}
}
//if ( db.mallocFailed != 0 )
//{
// sqlite3DbFree( db, ref zName );
// break;
//}
/* Make sure the column name is unique. If the name is not unique,
** append a integer to the name so that it becomes unique.
*/
nName = sqlite3Strlen30( zName );
for ( j = cnt = 0; j < i; j++ )
{
if ( aCol[j].zName.Equals( zName, StringComparison.OrdinalIgnoreCase ) )
{
string zNewName;
//zName[nName] = 0;
zNewName = sqlite3MPrintf( db, "%s:%d", zName.Substring( 0, nName ), ++cnt );
sqlite3DbFree( db, ref zName );
zName = zNewName;
j = -1;
if ( zName.Length == 0 )
break;
}
}
pCol.zName = zName;
}
//if ( db.mallocFailed != 0 )
//{
// for ( j = 0 ; j < i ; j++ )
// {
// sqlite3DbFree( db, aCol[j].zName );
// }
// sqlite3DbFree( db, aCol );
// paCol = null;
// pnCol = 0;
// return SQLITE_NOMEM;
//}
return SQLITE_OK;
}
/*
** Add type and collation information to a column list based on
** a SELECT statement.
**
** The column list presumably came from selectColumnNamesFromExprList().
** The column list has only names, not types or collations. This
** routine goes through and adds the types and collations.
**
** This routine requires that all identifiers in the SELECT
** statement be resolved.
*/
static void selectAddColumnTypeAndCollation(
Parse pParse, /* Parsing contexts */
int nCol, /* Number of columns */
Column[] aCol, /* List of columns */
Select pSelect /* SELECT used to determine types and collations */
)
{
////sqlite3 db = pParse.db;
NameContext sNC;
Column pCol;
CollSeq pColl;
int i;
Expr p;
ExprList_item[] a;
Debug.Assert( pSelect != null );
Debug.Assert( ( pSelect.selFlags & SF_Resolved ) != 0 );
Debug.Assert( nCol == pSelect.pEList.nExpr /*|| db.mallocFailed != 0 */ );
// if ( db.mallocFailed != 0 ) return;
sNC = new NameContext();// memset( &sNC, 0, sizeof( sNC ) );
sNC.pSrcList = pSelect.pSrc;
a = pSelect.pEList.a;
for ( i = 0; i < nCol; i++ )//, pCol++ )
{
pCol = aCol[i];
p = a[i].pExpr;
string bDummy = null;
pCol.zType = columnType( sNC, p, ref bDummy, ref bDummy, ref bDummy );// sqlite3DbStrDup( db, columnType( sNC, p, 0, 0, 0 ) );
pCol.affinity = sqlite3ExprAffinity( p );
if ( pCol.affinity == 0 )
pCol.affinity = SQLITE_AFF_NONE;
pColl = sqlite3ExprCollSeq( pParse, p );
if ( pColl != null )
{
pCol.zColl = pColl.zName;// sqlite3DbStrDup( db, pColl.zName );
}
}
}
/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
static Table sqlite3ResultSetOfSelect( Parse pParse, Select pSelect )
{
Table pTab;
sqlite3 db = pParse.db;
int savedFlags;
savedFlags = db.flags;
db.flags &= ~SQLITE_FullColNames;
db.flags |= SQLITE_ShortColNames;
sqlite3SelectPrep( pParse, pSelect, null );
if ( pParse.nErr != 0 )
return null;
while ( pSelect.pPrior != null )
pSelect = pSelect.pPrior;
db.flags = savedFlags;
pTab = new Table();// sqlite3DbMallocZero( db, sizeof( Table ) );
if ( pTab == null )
{
return null;
}
/* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside
** is disabled */
Debug.Assert( db.lookaside.bEnabled == 0 );
pTab.nRef = 1;
pTab.zName = null;
pTab.nRowEst = 1000000;
selectColumnsFromExprList( pParse, pSelect.pEList, ref pTab.nCol, ref pTab.aCol );
selectAddColumnTypeAndCollation( pParse, pTab.nCol, pTab.aCol, pSelect );
pTab.iPKey = -1;
//if ( db.mallocFailed != 0 )
//{
// sqlite3DeleteTable(db, ref pTab );
// return null;
//}
return pTab;
}
/*
** Get a VDBE for the given parser context. Create a new one if necessary.
** If an error occurs, return NULL and leave a message in pParse.
*/
static Vdbe sqlite3GetVdbe( Parse pParse )
{
Vdbe v = pParse.pVdbe;
if ( v == null )
{
v = pParse.pVdbe = sqlite3VdbeCreate( pParse.db );
#if !SQLITE_OMIT_TRACE
if ( v != null )
{
sqlite3VdbeAddOp0( v, OP_Trace );
}
#endif
}
return v;
}
/*
** Compute the iLimit and iOffset fields of the SELECT based on the
** pLimit and pOffset expressions. pLimit and pOffset hold the expressions
** that appear in the original SQL statement after the LIMIT and OFFSET
** keywords. Or NULL if those keywords are omitted. iLimit and iOffset
** are the integer memory register numbers for counters used to compute
** the limit and offset. If there is no limit and/or offset, then
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit and pOffset. iLimit and
** iOffset should have been preset to appropriate default values
** (usually but not always -1) prior to calling this routine.
** Only if pLimit!=0 or pOffset!=0 do the limit registers get
** redefined. The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters( Parse pParse, Select p, int iBreak )
{
Vdbe v = null;
int iLimit = 0;
int iOffset;
int addr1, n = 0;
if ( p.iLimit != 0 )
return;
/*
** "LIMIT -1" always shows all rows. There is some
** contraversy about what the correct behavior should be.
** The current implementation interprets "LIMIT 0" to mean
** no rows.
*/
sqlite3ExprCacheClear( pParse );
Debug.Assert( p.pOffset == null || p.pLimit != null );
if ( p.pLimit != null )
{
p.iLimit = iLimit = ++pParse.nMem;
v = sqlite3GetVdbe( pParse );
if ( NEVER( v == null ) )
return; /* VDBE should have already been allocated */
if ( sqlite3ExprIsInteger( p.pLimit, ref n ) != 0 )
{
sqlite3VdbeAddOp2( v, OP_Integer, n, iLimit );
VdbeComment( v, "LIMIT counter" );
if ( n == 0 )
{
sqlite3VdbeAddOp2( v, OP_Goto, 0, iBreak );
}
else
{
if ( p.nSelectRow > (double)n )
p.nSelectRow = (double)n;
}
}
else
{
sqlite3ExprCode( pParse, p.pLimit, iLimit );
sqlite3VdbeAddOp1( v, OP_MustBeInt, iLimit );
#if SQLITE_DEBUG
VdbeComment( v, "LIMIT counter" );
#endif
sqlite3VdbeAddOp2( v, OP_IfZero, iLimit, iBreak );
}
if ( p.pOffset != null )
{
p.iOffset = iOffset = ++pParse.nMem;
pParse.nMem++; /* Allocate an extra register for limit+offset */
sqlite3ExprCode( pParse, p.pOffset, iOffset );
sqlite3VdbeAddOp1( v, OP_MustBeInt, iOffset );
#if SQLITE_DEBUG
VdbeComment( v, "OFFSET counter" );
#endif
addr1 = sqlite3VdbeAddOp1( v, OP_IfPos, iOffset );
sqlite3VdbeAddOp2( v, OP_Integer, 0, iOffset );
sqlite3VdbeJumpHere( v, addr1 );
sqlite3VdbeAddOp3( v, OP_Add, iLimit, iOffset, iOffset + 1 );
#if SQLITE_DEBUG
VdbeComment( v, "LIMIT+OFFSET" );
#endif
addr1 = sqlite3VdbeAddOp1( v, OP_IfPos, iLimit );
sqlite3VdbeAddOp2( v, OP_Integer, -1, iOffset + 1 );
sqlite3VdbeJumpHere( v, addr1 );
}
}
}
#if !SQLITE_OMIT_COMPOUND_SELECT
/*
** Return the appropriate collating sequence for the iCol-th column of
** the result set for the compound-select statement "p". Return NULL if
** the column has no default collating sequence.
**
** The collating sequence for the compound select is taken from the
** left-most term of the select that has a collating sequence.
*/
static CollSeq multiSelectCollSeq( Parse pParse, Select p, int iCol )
{
CollSeq pRet;
if ( p.pPrior != null )
{
pRet = multiSelectCollSeq( pParse, p.pPrior, iCol );
}
else
{
pRet = null;
}
Debug.Assert( iCol >= 0 );
if ( pRet == null && iCol < p.pEList.nExpr )
{
pRet = sqlite3ExprCollSeq( pParse, p.pEList.a[iCol].pExpr );
}
return pRet;
}
#endif // * SQLITE_OMIT_COMPOUND_SELECT */
/* Forward reference */
//static int multiSelectOrderBy(
// Parse* pParse, /* Parsing context */
// Select* p, /* The right-most of SELECTs to be coded */
// SelectDest* pDest /* What to do with query results */
//);
#if !SQLITE_OMIT_COMPOUND_SELECT
/*
** This routine is called to process a compound query form from
** two or more separate queries using UNION, UNION ALL, EXCEPT, or
** INTERSECT
**
** "p" points to the right-most of the two queries. the query on the
** left is p.pPrior. The left query could also be a compound query
** in which case this routine will be called recursively.
**
** The results of the total query are to be written into a destination
** of type eDest with parameter iParm.
**
** Example 1: Consider a three-way compound SQL statement.
**
** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
**
** This statement is parsed up as follows:
**
** SELECT c FROM t3
** |
** `----. SELECT b FROM t2
** |
** `-----. SELECT a FROM t1
**
** The arrows in the diagram above represent the Select.pPrior pointer.
** So if this routine is called with p equal to the t3 query, then
** pPrior will be the t2 query. p.op will be TK_UNION in this case.
**
** Notice that because of the way SQLite parses compound SELECTs, the
** individual selects always group from left to right.
*/
static int multiSelect(
Parse pParse, /* Parsing context */
Select p, /* The right-most of SELECTs to be coded */
SelectDest pDest /* What to do with query results */
)
{
int rc = SQLITE_OK; /* Success code from a subroutine */
Select pPrior; /* Another SELECT immediately to our left */
Vdbe v; /* Generate code to this VDBE */
SelectDest dest = new SelectDest(); /* Alternative data destination */
Select pDelete = null; /* Chain of simple selects to delete */
sqlite3 db; /* Database connection */
#if !SQLITE_OMIT_EXPLAIN
int iSub1 = 0; /* EQP id of left-hand query */
int iSub2 = 0; /* EQP id of right-hand query */
#endif
/* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only
** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
*/
Debug.Assert( p != null && p.pPrior != null ); /* Calling function guarantees this much */
db = pParse.db;
pPrior = p.pPrior;
Debug.Assert( pPrior.pRightmost != pPrior );
Debug.Assert( pPrior.pRightmost == p.pRightmost );
dest = pDest;
if ( pPrior.pOrderBy != null )
{
sqlite3ErrorMsg( pParse, "ORDER BY clause should come after %s not before",
selectOpName( p.op ) );
rc = 1;
goto multi_select_end;
}
if ( pPrior.pLimit != null )
{
sqlite3ErrorMsg( pParse, "LIMIT clause should come after %s not before",
selectOpName( p.op ) );
rc = 1;
goto multi_select_end;
}
v = sqlite3GetVdbe( pParse );
Debug.Assert( v != null ); /* The VDBE already created by calling function */
/* Create the destination temporary table if necessary
*/
if ( dest.eDest == SRT_EphemTab )
{
Debug.Assert( p.pEList != null );
sqlite3VdbeAddOp2( v, OP_OpenEphemeral, dest.iParm, p.pEList.nExpr );
sqlite3VdbeChangeP5( v, BTREE_UNORDERED );
dest.eDest = SRT_Table;
}
/* Make sure all SELECTs in the statement have the same number of elements
** in their result sets.
*/
Debug.Assert( p.pEList != null && pPrior.pEList != null );
if ( p.pEList.nExpr != pPrior.pEList.nExpr )
{
sqlite3ErrorMsg( pParse, "SELECTs to the left and right of %s" +
" do not have the same number of result columns", selectOpName( p.op ) );
rc = 1;
goto multi_select_end;
}
/* Compound SELECTs that have an ORDER BY clause are handled separately.
*/
if ( p.pOrderBy != null )
{
return multiSelectOrderBy( pParse, p, pDest );
}
/* Generate code for the left and right SELECT statements.
*/
switch ( p.op )
{
case TK_ALL:
{
int addr = 0;
int nLimit = 0;
Debug.Assert( pPrior.pLimit == null );
pPrior.pLimit = p.pLimit;
pPrior.pOffset = p.pOffset;
explainSetInteger( ref iSub1, pParse.iNextSelectId );
rc = sqlite3Select( pParse, pPrior, ref dest );
p.pLimit = null;
p.pOffset = null;
if ( rc != 0 )
{
goto multi_select_end;
}
p.pPrior = null;
p.iLimit = pPrior.iLimit;
p.iOffset = pPrior.iOffset;
if ( p.iLimit != 0 )
{
addr = sqlite3VdbeAddOp1( v, OP_IfZero, p.iLimit );
#if SQLITE_DEBUG
VdbeComment( v, "Jump ahead if LIMIT reached" );
#endif
}
explainSetInteger( ref iSub2, pParse.iNextSelectId );
rc = sqlite3Select( pParse, p, ref dest );
testcase( rc != SQLITE_OK );
pDelete = p.pPrior;
p.pPrior = pPrior;
p.nSelectRow += pPrior.nSelectRow;
if ( pPrior.pLimit != null
&& sqlite3ExprIsInteger( pPrior.pLimit, ref nLimit ) != 0
&& p.nSelectRow > (double)nLimit
)
{
p.nSelectRow = (double)nLimit;
}
if ( addr != 0 )
{
sqlite3VdbeJumpHere( v, addr );
}
break;
}
case TK_EXCEPT:
case TK_UNION:
{
int unionTab; /* VdbeCursor number of the temporary table holding result */
u8 op = 0; /* One of the SRT_ operations to apply to self */
int priorOp; /* The SRT_ operation to apply to prior selects */
Expr pLimit, pOffset; /* Saved values of p.nLimit and p.nOffset */
int addr;
SelectDest uniondest = new SelectDest();
testcase( p.op == TK_EXCEPT );
testcase( p.op == TK_UNION );
priorOp = SRT_Union;
if ( dest.eDest == priorOp && ALWAYS( null == p.pLimit && null == p.pOffset ) )
{
/* We can reuse a temporary table generated by a SELECT to our
** right.
*/
Debug.Assert( p.pRightmost != p ); /* Can only happen for leftward elements
** of a 3-way or more compound */
Debug.Assert( p.pLimit == null ); /* Not allowed on leftward elements */
Debug.Assert( p.pOffset == null ); /* Not allowed on leftward elements */
unionTab = dest.iParm;
}
else
{
/* We will need to create our own temporary table to hold the
** intermediate results.
*/
unionTab = pParse.nTab++;
Debug.Assert( p.pOrderBy == null );
addr = sqlite3VdbeAddOp2( v, OP_OpenEphemeral, unionTab, 0 );
Debug.Assert( p.addrOpenEphm[0] == -1 );
p.addrOpenEphm[0] = addr;
p.pRightmost.selFlags |= SF_UsesEphemeral;
Debug.Assert( p.pEList != null );
}
/* Code the SELECT statements to our left
*/
Debug.Assert( pPrior.pOrderBy == null );
sqlite3SelectDestInit( uniondest, priorOp, unionTab );
explainSetInteger( ref iSub1, pParse.iNextSelectId );
rc = sqlite3Select( pParse, pPrior, ref uniondest );
if ( rc != 0 )
{
goto multi_select_end;
}
/* Code the current SELECT statement
*/
if ( p.op == TK_EXCEPT )
{
op = SRT_Except;
}
else
{
Debug.Assert( p.op == TK_UNION );
op = SRT_Union;
}
p.pPrior = null;
pLimit = p.pLimit;
p.pLimit = null;
pOffset = p.pOffset;
p.pOffset = null;
uniondest.eDest = op;
explainSetInteger( ref iSub2, pParse.iNextSelectId );
rc = sqlite3Select( pParse, p, ref uniondest );
testcase( rc != SQLITE_OK );
/* Query flattening in sqlite3Select() might refill p.pOrderBy.
** Be sure to delete p.pOrderBy, therefore, to avoid a memory leak. */
sqlite3ExprListDelete( db, ref p.pOrderBy );
pDelete = p.pPrior;
p.pPrior = pPrior;
p.pOrderBy = null;
if ( p.op == TK_UNION )
p.nSelectRow += pPrior.nSelectRow;
sqlite3ExprDelete( db, ref p.pLimit );
p.pLimit = pLimit;
p.pOffset = pOffset;
p.iLimit = 0;
p.iOffset = 0;
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
Debug.Assert( unionTab == dest.iParm || dest.eDest != priorOp );
if ( dest.eDest != priorOp )
{
int iCont, iBreak, iStart;
Debug.Assert( p.pEList != null );
if ( dest.eDest == SRT_Output )
{
Select pFirst = p;
while ( pFirst.pPrior != null )
pFirst = pFirst.pPrior;
generateColumnNames( pParse, null, pFirst.pEList );
}
iBreak = sqlite3VdbeMakeLabel( v );
iCont = sqlite3VdbeMakeLabel( v );
computeLimitRegisters( pParse, p, iBreak );
sqlite3VdbeAddOp2( v, OP_Rewind, unionTab, iBreak );
iStart = sqlite3VdbeCurrentAddr( v );
selectInnerLoop( pParse, p, p.pEList, unionTab, p.pEList.nExpr,
null, -1, dest, iCont, iBreak );
sqlite3VdbeResolveLabel( v, iCont );
sqlite3VdbeAddOp2( v, OP_Next, unionTab, iStart );
sqlite3VdbeResolveLabel( v, iBreak );
sqlite3VdbeAddOp2( v, OP_Close, unionTab, 0 );
}
break;
}
default:
Debug.Assert( p.op == TK_INTERSECT );
{
int tab1, tab2;
int iCont, iBreak, iStart;
Expr pLimit, pOffset;
int addr;
SelectDest intersectdest = new SelectDest();
int r1;
/* INTERSECT is different from the others since it requires
** two temporary tables. Hence it has its own case. Begin
** by allocating the tables we will need.
*/
tab1 = pParse.nTab++;
tab2 = pParse.nTab++;
Debug.Assert( p.pOrderBy == null );
addr = sqlite3VdbeAddOp2( v, OP_OpenEphemeral, tab1, 0 );
Debug.Assert( p.addrOpenEphm[0] == -1 );
p.addrOpenEphm[0] = addr;
p.pRightmost.selFlags |= SF_UsesEphemeral;
Debug.Assert( p.pEList != null );
/* Code the SELECTs to our left into temporary table "tab1".
*/
sqlite3SelectDestInit( intersectdest, SRT_Union, tab1 );
explainSetInteger( ref iSub1, pParse.iNextSelectId );
rc = sqlite3Select( pParse, pPrior, ref intersectdest );
if ( rc != 0 )
{
goto multi_select_end;
}
/* Code the current SELECT into temporary table "tab2"
*/
addr = sqlite3VdbeAddOp2( v, OP_OpenEphemeral, tab2, 0 );
Debug.Assert( p.addrOpenEphm[1] == -1 );
p.addrOpenEphm[1] = addr;
p.pPrior = null;
pLimit = p.pLimit;
p.pLimit = null;
pOffset = p.pOffset;
p.pOffset = null;
intersectdest.iParm = tab2;
explainSetInteger( ref iSub2, pParse.iNextSelectId );
rc = sqlite3Select( pParse, p, ref intersectdest );
testcase( rc != SQLITE_OK );
p.pPrior = pPrior;
if ( p.nSelectRow > pPrior.nSelectRow )
p.nSelectRow = pPrior.nSelectRow;
sqlite3ExprDelete( db, ref p.pLimit );
p.pLimit = pLimit;
p.pOffset = pOffset;
/* Generate code to take the intersection of the two temporary
** tables.
*/
Debug.Assert( p.pEList != null );
if ( dest.eDest == SRT_Output )
{
Select pFirst = p;
while ( pFirst.pPrior != null )
pFirst = pFirst.pPrior;
generateColumnNames( pParse, null, pFirst.pEList );
}
iBreak = sqlite3VdbeMakeLabel( v );
iCont = sqlite3VdbeMakeLabel( v );
computeLimitRegisters( pParse, p, iBreak );
sqlite3VdbeAddOp2( v, OP_Rewind, tab1, iBreak );
r1 = sqlite3GetTempReg( pParse );
iStart = sqlite3VdbeAddOp2( v, OP_RowKey, tab1, r1 );
sqlite3VdbeAddOp4Int( v, OP_NotFound, tab2, iCont, r1, 0 );
sqlite3ReleaseTempReg( pParse, r1 );
selectInnerLoop( pParse, p, p.pEList, tab1, p.pEList.nExpr,
null, -1, dest, iCont, iBreak );
sqlite3VdbeResolveLabel( v, iCont );
sqlite3VdbeAddOp2( v, OP_Next, tab1, iStart );
sqlite3VdbeResolveLabel( v, iBreak );
sqlite3VdbeAddOp2( v, OP_Close, tab2, 0 );
sqlite3VdbeAddOp2( v, OP_Close, tab1, 0 );
break;
}
}
explainComposite( pParse, p.op, iSub1, iSub2, p.op != TK_ALL );
/* Compute collating sequences used by
** temporary tables needed to implement the compound select.
** Attach the KeyInfo structure to all temporary tables.
**
** This section is run by the right-most SELECT statement only.
** SELECT statements to the left always skip this part. The right-most
** SELECT might also skip this part if it has no ORDER BY clause and
** no temp tables are required.
*/
if ( ( p.selFlags & SF_UsesEphemeral ) != 0 )
{
int i; /* Loop counter */
KeyInfo pKeyInfo; /* Collating sequence for the result set */
Select pLoop; /* For looping through SELECT statements */
CollSeq apColl; /* For looping through pKeyInfo.aColl[] */
int nCol; /* Number of columns in result set */
Debug.Assert( p.pRightmost == p );
nCol = p.pEList.nExpr;
pKeyInfo = new KeyInfo(); //sqlite3DbMallocZero(db,
pKeyInfo.aColl = new CollSeq[nCol]; //sizeof(*pKeyInfo)+nCol*(CollSeq*.Length + 1));
//if ( pKeyInfo == null )
//{
// rc = SQLITE_NOMEM;
// goto multi_select_end;
//}
pKeyInfo.enc = db.aDbStatic[0].pSchema.enc;// ENC( pParse.db );
pKeyInfo.nField = (u16)nCol;
for ( i = 0; i < nCol; i++ )
{//, apColl++){
apColl = multiSelectCollSeq( pParse, p, i );
if ( null == apColl )
{
apColl = db.pDfltColl;
}
pKeyInfo.aColl[i] = apColl;
}
for ( pLoop = p; pLoop != null; pLoop = pLoop.pPrior )
{
for ( i = 0; i < 2; i++ )
{
int addr = pLoop.addrOpenEphm[i];
if ( addr < 0 )
{
/* If [0] is unused then [1] is also unused. So we can
** always safely abort as soon as the first unused slot is found */
Debug.Assert( pLoop.addrOpenEphm[1] < 0 );
break;
}
sqlite3VdbeChangeP2( v, addr, nCol );
sqlite3VdbeChangeP4( v, addr, pKeyInfo, P4_KEYINFO );
pLoop.addrOpenEphm[i] = -1;
}
}
sqlite3DbFree( db, ref pKeyInfo );
}
multi_select_end:
pDest.iMem = dest.iMem;
pDest.nMem = dest.nMem;
sqlite3SelectDelete( db, ref pDelete );
return rc;
}
#endif // * SQLITE_OMIT_COMPOUND_SELECT */
/*
** Code an output subroutine for a coroutine implementation of a
** SELECT statment.
**
** The data to be output is contained in pIn.iMem. There are
** pIn.nMem columns to be output. pDest is where the output should
** be sent.
**
** regReturn is the number of the register holding the subroutine
** return address.
**
** If regPrev>0 then it is the first register in a vector that
** records the previous output. mem[regPrev] is a flag that is false
** if there has been no previous output. If regPrev>0 then code is
** generated to suppress duplicates. pKeyInfo is used for comparing
** keys.
**
** If the LIMIT found in p.iLimit is reached, jump immediately to
** iBreak.
*/
static int generateOutputSubroutine(
Parse pParse, /* Parsing context */
Select p, /* The SELECT statement */
SelectDest pIn, /* Coroutine supplying data */
SelectDest pDest, /* Where to send the data */
int regReturn, /* The return address register */
int regPrev, /* Previous result register. No uniqueness if 0 */
KeyInfo pKeyInfo, /* For comparing with previous entry */
int p4type, /* The p4 type for pKeyInfo */
int iBreak /* Jump here if we hit the LIMIT */
)
{
Vdbe v = pParse.pVdbe;
int iContinue;
int addr;
addr = sqlite3VdbeCurrentAddr( v );
iContinue = sqlite3VdbeMakeLabel( v );
/* Suppress duplicates for UNION, EXCEPT, and INTERSECT
*/
if ( regPrev != 0 )
{
int j1, j2;
j1 = sqlite3VdbeAddOp1( v, OP_IfNot, regPrev );
j2 = sqlite3VdbeAddOp4( v, OP_Compare, pIn.iMem, regPrev + 1, pIn.nMem,
pKeyInfo, p4type );
sqlite3VdbeAddOp3( v, OP_Jump, j2 + 2, iContinue, j2 + 2 );
sqlite3VdbeJumpHere( v, j1 );
sqlite3ExprCodeCopy( pParse, pIn.iMem, regPrev + 1, pIn.nMem );
sqlite3VdbeAddOp2( v, OP_Integer, 1, regPrev );
}
//if ( pParse.db.mallocFailed != 0 ) return 0;
/* Suppress the the first OFFSET entries if there is an OFFSET clause
*/
codeOffset( v, p, iContinue );
switch ( pDest.eDest )
{
/* Store the result as data using a unique key.
*/
case SRT_Table:
case SRT_EphemTab:
{
int r1 = sqlite3GetTempReg( pParse );
int r2 = sqlite3GetTempReg( pParse );
testcase( pDest.eDest == SRT_Table );
testcase( pDest.eDest == SRT_EphemTab );
sqlite3VdbeAddOp3( v, OP_MakeRecord, pIn.iMem, pIn.nMem, r1 );
sqlite3VdbeAddOp2( v, OP_NewRowid, pDest.iParm, r2 );
sqlite3VdbeAddOp3( v, OP_Insert, pDest.iParm, r1, r2 );
sqlite3VdbeChangeP5( v, OPFLAG_APPEND );
sqlite3ReleaseTempReg( pParse, r2 );
sqlite3ReleaseTempReg( pParse, r1 );
break;
}
#if !SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)" construct,
** then there should be a single item on the stack. Write this
** item into the set table with bogus data.
*/
case SRT_Set:
{
int r1;
Debug.Assert( pIn.nMem == 1 );
p.affinity =
sqlite3CompareAffinity( p.pEList.a[0].pExpr, pDest.affinity );
r1 = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp4( v, OP_MakeRecord, pIn.iMem, 1, r1, p.affinity, 1 );
sqlite3ExprCacheAffinityChange( pParse, pIn.iMem, 1 );
sqlite3VdbeAddOp2( v, OP_IdxInsert, pDest.iParm, r1 );
sqlite3ReleaseTempReg( pParse, r1 );
break;
}
#if FALSE //* Never occurs on an ORDER BY query */
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp2(v, OP_Integer, 1, pDest.iParm);
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell and break out
** of the scan loop.
*/
case SRT_Mem:
{
Debug.Assert( pIn.nMem == 1 );
sqlite3ExprCodeMove( pParse, pIn.iMem, pDest.iParm, 1 );
/* The LIMIT clause will jump out of the loop for us */
break;
}
#endif //* #if !SQLITE_OMIT_SUBQUERY */
/* The results are stored in a sequence of registers
** starting at pDest.iMem. Then the co-routine yields.
*/
case SRT_Coroutine:
{
if ( pDest.iMem == 0 )
{
pDest.iMem = sqlite3GetTempRange( pParse, pIn.nMem );
pDest.nMem = pIn.nMem;
}
sqlite3ExprCodeMove( pParse, pIn.iMem, pDest.iMem, pDest.nMem );
sqlite3VdbeAddOp1( v, OP_Yield, pDest.iParm );
break;
}
/* If none of the above, then the result destination must be
** SRT_Output. This routine is never called with any other
** destination other than the ones handled above or SRT_Output.
**
** For SRT_Output, results are stored in a sequence of registers.
** Then the OP_ResultRow opcode is used to cause sqlite3_step() to
** return the next row of result.
*/
default:
{
Debug.Assert( pDest.eDest == SRT_Output );
sqlite3VdbeAddOp2( v, OP_ResultRow, pIn.iMem, pIn.nMem );
sqlite3ExprCacheAffinityChange( pParse, pIn.iMem, pIn.nMem );
break;
}
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if ( p.iLimit != 0 )
{
sqlite3VdbeAddOp3( v, OP_IfZero, p.iLimit, iBreak, -1 );
}
/* Generate the subroutine return
*/
sqlite3VdbeResolveLabel( v, iContinue );
sqlite3VdbeAddOp1( v, OP_Return, regReturn );
return addr;
}
/*
** Alternative compound select code generator for cases when there
** is an ORDER BY clause.
**
** We assume a query of the following form:
**
** <selectA> <operator> <selectB> ORDER BY <orderbylist>
**
** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea
** is to code both <selectA> and <selectB> with the ORDER BY clause as
** co-routines. Then run the co-routines in parallel and merge the results
** into the output. In addition to the two coroutines (called selectA and
** selectB) there are 7 subroutines:
**
** outA: Move the output of the selectA coroutine into the output
** of the compound query.
**
** outB: Move the output of the selectB coroutine into the output
** of the compound query. (Only generated for UNION and
** UNION ALL. EXCEPT and INSERTSECT never output a row that
** appears only in B.)
**
** AltB: Called when there is data from both coroutines and A<B.
**
** AeqB: Called when there is data from both coroutines and A==B.
**
** AgtB: Called when there is data from both coroutines and A>B.
**
** EofA: Called when data is exhausted from selectA.
**
** EofB: Called when data is exhausted from selectB.
**
** The implementation of the latter five subroutines depend on which
** <operator> is used:
**
**
** UNION ALL UNION EXCEPT INTERSECT
** ------------- ----------------- -------------- -----------------
** AltB: outA, nextA outA, nextA outA, nextA nextA
**
** AeqB: outA, nextA nextA nextA outA, nextA
**
** AgtB: outB, nextB outB, nextB nextB nextB
**
** EofA: outB, nextB outB, nextB halt halt
**
** EofB: outA, nextA outA, nextA outA, nextA halt
**
** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
** causes an immediate jump to EofA and an EOF on B following nextB causes
** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or
** following nextX causes a jump to the end of the select processing.
**
** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
** within the output subroutine. The regPrev register set holds the previously
** output value. A comparison is made against this value and the output
** is skipped if the next results would be the same as the previous.
**
** The implementation plan is to implement the two coroutines and seven
** subroutines first, then put the control logic at the bottom. Like this:
**
** goto Init
** coA: coroutine for left query (A)
** coB: coroutine for right query (B)
** outA: output one row of A
** outB: output one row of B (UNION and UNION ALL only)
** EofA: ...
** EofB: ...
** AltB: ...
** AeqB: ...
** AgtB: ...
** Init: initialize coroutine registers
** yield coA
** if eof(A) goto EofA
** yield coB
** if eof(B) goto EofB
** Cmpr: Compare A, B
** Jump AltB, AeqB, AgtB
** End: ...
**
** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
** actually called using Gosub and they do not Return. EofA and EofB loop
** until all data is exhausted then jump to the "end" labe. AltB, AeqB,
** and AgtB jump to either L2 or to one of EofA or EofB.
*/
#if !SQLITE_OMIT_COMPOUND_SELECT
static int multiSelectOrderBy(
Parse pParse, /* Parsing context */
Select p, /* The right-most of SELECTs to be coded */
SelectDest pDest /* What to do with query results */
)
{
int i, j; /* Loop counters */
Select pPrior; /* Another SELECT immediately to our left */
Vdbe v; /* Generate code to this VDBE */
SelectDest destA = new SelectDest(); /* Destination for coroutine A */
SelectDest destB = new SelectDest(); /* Destination for coroutine B */
int regAddrA; /* Address register for select-A coroutine */
int regEofA; /* Flag to indicate when select-A is complete */
int regAddrB; /* Address register for select-B coroutine */
int regEofB; /* Flag to indicate when select-B is complete */
int addrSelectA; /* Address of the select-A coroutine */
int addrSelectB; /* Address of the select-B coroutine */
int regOutA; /* Address register for the output-A subroutine */
int regOutB; /* Address register for the output-B subroutine */
int addrOutA; /* Address of the output-A subroutine */
int addrOutB = 0; /* Address of the output-B subroutine */
int addrEofA; /* Address of the select-A-exhausted subroutine */
int addrEofB; /* Address of the select-B-exhausted subroutine */
int addrAltB; /* Address of the A<B subroutine */
int addrAeqB; /* Address of the A==B subroutine */
int addrAgtB; /* Address of the A>B subroutine */
int regLimitA; /* Limit register for select-A */
int regLimitB; /* Limit register for select-A */
int regPrev; /* A range of registers to hold previous output */
int savedLimit; /* Saved value of p.iLimit */
int savedOffset; /* Saved value of p.iOffset */
int labelCmpr; /* Label for the start of the merge algorithm */
int labelEnd; /* Label for the end of the overall SELECT stmt */
int j1; /* Jump instructions that get retargetted */
int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
KeyInfo pKeyDup = null; /* Comparison information for duplicate removal */
KeyInfo pKeyMerge; /* Comparison information for merging rows */
sqlite3 db; /* Database connection */
ExprList pOrderBy; /* The ORDER BY clause */
int nOrderBy; /* Number of terms in the ORDER BY clause */
int[] aPermute; /* Mapping from ORDER BY terms to result set columns */
#if !SQLITE_OMIT_EXPLAIN
int iSub1 = 0; /* EQP id of left-hand query */
int iSub2 = 0; /* EQP id of right-hand query */
#endif
Debug.Assert( p.pOrderBy != null );
Debug.Assert( pKeyDup == null ); /* "Managed" code needs this. Ticket #3382. */
db = pParse.db;
v = pParse.pVdbe;
Debug.Assert( v != null ); /* Already thrown the error if VDBE alloc failed */
labelEnd = sqlite3VdbeMakeLabel( v );
labelCmpr = sqlite3VdbeMakeLabel( v );
/* Patch up the ORDER BY clause
*/
op = p.op;
pPrior = p.pPrior;
Debug.Assert( pPrior.pOrderBy == null );
pOrderBy = p.pOrderBy;
Debug.Assert( pOrderBy != null );
nOrderBy = pOrderBy.nExpr;
/* For operators other than UNION ALL we have to make sure that
** the ORDER BY clause covers every term of the result set. Add
** terms to the ORDER BY clause as necessary.
*/
if ( op != TK_ALL )
{
for ( i = 1; /* db.mallocFailed == 0 && */ i <= p.pEList.nExpr; i++ )
{
ExprList_item pItem;
for ( j = 0; j < nOrderBy; j++ )//, pItem++)
{
pItem = pOrderBy.a[j];
Debug.Assert( pItem.iCol > 0 );
if ( pItem.iCol == i )
break;
}
if ( j == nOrderBy )
{
Expr pNew = sqlite3Expr( db, TK_INTEGER, null );
//if ( pNew == null )
// return SQLITE_NOMEM;
pNew.flags |= EP_IntValue;
pNew.u.iValue = i;
pOrderBy = sqlite3ExprListAppend( pParse, pOrderBy, pNew );
pOrderBy.a[nOrderBy++].iCol = (u16)i;
}
}
}
/* Compute the comparison permutation and keyinfo that is used with
** the permutation used to determine if the next
** row of results comes from selectA or selectB. Also add explicit
** collations to the ORDER BY clause terms so that when the subqueries
** to the right and the left are evaluated, they use the correct
** collation.
*/
aPermute = new int[nOrderBy];// sqlite3DbMallocRaw( db, sizeof( int ) * nOrderBy );
if ( aPermute != null )
{
ExprList_item pItem;
for ( i = 0; i < nOrderBy; i++ )//, pItem++)
{
pItem = pOrderBy.a[i];
Debug.Assert( pItem.iCol > 0 && pItem.iCol <= p.pEList.nExpr );
aPermute[i] = pItem.iCol - 1;
}
pKeyMerge = new KeyInfo();// sqlite3DbMallocRaw(db, sizeof(*pKeyMerge)+nOrderBy*(sizeof(CollSeq)+1));
if ( pKeyMerge != null )
{
pKeyMerge.aColl = new CollSeq[nOrderBy];
pKeyMerge.aSortOrder = new byte[nOrderBy];//(u8)&pKeyMerge.aColl[nOrderBy];
pKeyMerge.nField = (u16)nOrderBy;
pKeyMerge.enc = ENC( db );
for ( i = 0; i < nOrderBy; i++ )
{
CollSeq pColl;
Expr pTerm = pOrderBy.a[i].pExpr;
if ( ( pTerm.flags & EP_ExpCollate ) != 0 )
{
pColl = pTerm.pColl;
}
else
{
pColl = multiSelectCollSeq( pParse, p, aPermute[i] );
pTerm.flags |= EP_ExpCollate;
pTerm.pColl = pColl;
}
pKeyMerge.aColl[i] = pColl;
pKeyMerge.aSortOrder[i] = (byte)pOrderBy.a[i].sortOrder;
}
}
}
else
{
pKeyMerge = null;
}
/* Reattach the ORDER BY clause to the query.
*/
p.pOrderBy = pOrderBy;
pPrior.pOrderBy = sqlite3ExprListDup( pParse.db, pOrderBy, 0 );
/* Allocate a range of temporary registers and the KeyInfo needed
** for the logic that removes duplicate result rows when the
** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
*/
if ( op == TK_ALL )
{
regPrev = 0;
}
else
{
int nExpr = p.pEList.nExpr;
Debug.Assert( nOrderBy >= nExpr /*|| db.mallocFailed != 0 */ );
regPrev = sqlite3GetTempRange( pParse, nExpr + 1 );
sqlite3VdbeAddOp2( v, OP_Integer, 0, regPrev );
pKeyDup = new KeyInfo();//sqlite3DbMallocZero(db,
//sizeof(*pKeyDup) + nExpr*(sizeof(CollSeq)+1) );
if ( pKeyDup != null )
{
pKeyDup.aColl = new CollSeq[nExpr];
pKeyDup.aSortOrder = new byte[nExpr];//(u8)&pKeyDup.aColl[nExpr];
pKeyDup.nField = (u16)nExpr;
pKeyDup.enc = ENC( db );
for ( i = 0; i < nExpr; i++ )
{
pKeyDup.aColl[i] = multiSelectCollSeq( pParse, p, i );
pKeyDup.aSortOrder[i] = 0;
}
}
}
/* Separate the left and the right query from one another
*/
p.pPrior = null;
sqlite3ResolveOrderGroupBy( pParse, p, p.pOrderBy, "ORDER" );
if ( pPrior.pPrior == null )
{
sqlite3ResolveOrderGroupBy( pParse, pPrior, pPrior.pOrderBy, "ORDER" );
}
/* Compute the limit registers */
computeLimitRegisters( pParse, p, labelEnd );
if ( p.iLimit != 0 && op == TK_ALL )
{
regLimitA = ++pParse.nMem;
regLimitB = ++pParse.nMem;
sqlite3VdbeAddOp2( v, OP_Copy, ( p.iOffset != 0 ) ? p.iOffset + 1 : p.iLimit,
regLimitA );
sqlite3VdbeAddOp2( v, OP_Copy, regLimitA, regLimitB );
}
else
{
regLimitA = regLimitB = 0;
}
sqlite3ExprDelete( db, ref p.pLimit );
p.pLimit = null;
sqlite3ExprDelete( db, ref p.pOffset );
p.pOffset = null;
regAddrA = ++pParse.nMem;
regEofA = ++pParse.nMem;
regAddrB = ++pParse.nMem;
regEofB = ++pParse.nMem;
regOutA = ++pParse.nMem;
regOutB = ++pParse.nMem;
sqlite3SelectDestInit( destA, SRT_Coroutine, regAddrA );
sqlite3SelectDestInit( destB, SRT_Coroutine, regAddrB );
/* Jump past the various subroutines and coroutines to the main
** merge loop
*/
j1 = sqlite3VdbeAddOp0( v, OP_Goto );
addrSelectA = sqlite3VdbeCurrentAddr( v );
/* Generate a coroutine to evaluate the SELECT statement to the
** left of the compound operator - the "A" select.
*/
VdbeNoopComment( v, "Begin coroutine for left SELECT" );
pPrior.iLimit = regLimitA;
explainSetInteger( ref iSub1, pParse.iNextSelectId );
sqlite3Select( pParse, pPrior, ref destA );
sqlite3VdbeAddOp2( v, OP_Integer, 1, regEofA );
sqlite3VdbeAddOp1( v, OP_Yield, regAddrA );
VdbeNoopComment( v, "End coroutine for left SELECT" );
/* Generate a coroutine to evaluate the SELECT statement on
** the right - the "B" select
*/
addrSelectB = sqlite3VdbeCurrentAddr( v );
VdbeNoopComment( v, "Begin coroutine for right SELECT" );
savedLimit = p.iLimit;
savedOffset = p.iOffset;
p.iLimit = regLimitB;
p.iOffset = 0;
explainSetInteger( ref iSub2, pParse.iNextSelectId );
sqlite3Select( pParse, p, ref destB );
p.iLimit = savedLimit;
p.iOffset = savedOffset;
sqlite3VdbeAddOp2( v, OP_Integer, 1, regEofB );
sqlite3VdbeAddOp1( v, OP_Yield, regAddrB );
VdbeNoopComment( v, "End coroutine for right SELECT" );
/* Generate a subroutine that outputs the current row of the A
** select as the next output row of the compound select.
*/
VdbeNoopComment( v, "Output routine for A" );
addrOutA = generateOutputSubroutine( pParse,
p, destA, pDest, regOutA,
regPrev, pKeyDup, P4_KEYINFO_HANDOFF, labelEnd );
/* Generate a subroutine that outputs the current row of the B
** select as the next output row of the compound select.
*/
if ( op == TK_ALL || op == TK_UNION )
{
VdbeNoopComment( v, "Output routine for B" );
addrOutB = generateOutputSubroutine( pParse,
p, destB, pDest, regOutB,
regPrev, pKeyDup, P4_KEYINFO_STATIC, labelEnd );
}
/* Generate a subroutine to run when the results from select A
** are exhausted and only data in select B remains.
*/
VdbeNoopComment( v, "eof-A subroutine" );
if ( op == TK_EXCEPT || op == TK_INTERSECT )
{
addrEofA = sqlite3VdbeAddOp2( v, OP_Goto, 0, labelEnd );
}
else
{
addrEofA = sqlite3VdbeAddOp2( v, OP_If, regEofB, labelEnd );
sqlite3VdbeAddOp2( v, OP_Gosub, regOutB, addrOutB );
sqlite3VdbeAddOp1( v, OP_Yield, regAddrB );
sqlite3VdbeAddOp2( v, OP_Goto, 0, addrEofA );
p.nSelectRow += pPrior.nSelectRow;
}
/* Generate a subroutine to run when the results from select B
** are exhausted and only data in select A remains.
*/
if ( op == TK_INTERSECT )
{
addrEofB = addrEofA;
if ( p.nSelectRow > pPrior.nSelectRow )
p.nSelectRow = pPrior.nSelectRow;
}
else
{
VdbeNoopComment( v, "eof-B subroutine" );
addrEofB = sqlite3VdbeAddOp2( v, OP_If, regEofA, labelEnd );
sqlite3VdbeAddOp2( v, OP_Gosub, regOutA, addrOutA );
sqlite3VdbeAddOp1( v, OP_Yield, regAddrA );
sqlite3VdbeAddOp2( v, OP_Goto, 0, addrEofB );
}
/* Generate code to handle the case of A<B
*/
VdbeNoopComment( v, "A-lt-B subroutine" );
addrAltB = sqlite3VdbeAddOp2( v, OP_Gosub, regOutA, addrOutA );
sqlite3VdbeAddOp1( v, OP_Yield, regAddrA );
sqlite3VdbeAddOp2( v, OP_If, regEofA, addrEofA );
sqlite3VdbeAddOp2( v, OP_Goto, 0, labelCmpr );
/* Generate code to handle the case of A==B
*/
if ( op == TK_ALL )
{
addrAeqB = addrAltB;
}
else if ( op == TK_INTERSECT )
{
addrAeqB = addrAltB;
addrAltB++;
}
else
{
VdbeNoopComment( v, "A-eq-B subroutine" );
addrAeqB =
sqlite3VdbeAddOp1( v, OP_Yield, regAddrA );
sqlite3VdbeAddOp2( v, OP_If, regEofA, addrEofA );
sqlite3VdbeAddOp2( v, OP_Goto, 0, labelCmpr );
}
/* Generate code to handle the case of A>B
*/
VdbeNoopComment( v, "A-gt-B subroutine" );
addrAgtB = sqlite3VdbeCurrentAddr( v );
if ( op == TK_ALL || op == TK_UNION )
{
sqlite3VdbeAddOp2( v, OP_Gosub, regOutB, addrOutB );
}
sqlite3VdbeAddOp1( v, OP_Yield, regAddrB );
sqlite3VdbeAddOp2( v, OP_If, regEofB, addrEofB );
sqlite3VdbeAddOp2( v, OP_Goto, 0, labelCmpr );
/* This code runs once to initialize everything.
*/
sqlite3VdbeJumpHere( v, j1 );
sqlite3VdbeAddOp2( v, OP_Integer, 0, regEofA );
sqlite3VdbeAddOp2( v, OP_Integer, 0, regEofB );
sqlite3VdbeAddOp2( v, OP_Gosub, regAddrA, addrSelectA );
sqlite3VdbeAddOp2( v, OP_Gosub, regAddrB, addrSelectB );
sqlite3VdbeAddOp2( v, OP_If, regEofA, addrEofA );
sqlite3VdbeAddOp2( v, OP_If, regEofB, addrEofB );
/* Implement the main merge loop
*/
sqlite3VdbeResolveLabel( v, labelCmpr );
sqlite3VdbeAddOp4( v, OP_Permutation, 0, 0, 0, aPermute, P4_INTARRAY );
sqlite3VdbeAddOp4( v, OP_Compare, destA.iMem, destB.iMem, nOrderBy,
pKeyMerge, P4_KEYINFO_HANDOFF );
sqlite3VdbeAddOp3( v, OP_Jump, addrAltB, addrAeqB, addrAgtB );
/* Release temporary registers
*/
if ( regPrev != 0 )
{
sqlite3ReleaseTempRange( pParse, regPrev, nOrderBy + 1 );
}
/* Jump to the this point in order to terminate the query.
*/
sqlite3VdbeResolveLabel( v, labelEnd );
/* Set the number of output columns
*/
if ( pDest.eDest == SRT_Output )
{
Select pFirst = pPrior;
while ( pFirst.pPrior != null )
pFirst = pFirst.pPrior;
generateColumnNames( pParse, null, pFirst.pEList );
}
/* Reassembly the compound query so that it will be freed correctly
** by the calling function */
if ( p.pPrior != null )
{
sqlite3SelectDelete( db, ref p.pPrior );
}
p.pPrior = pPrior;
/*** TBD: Insert subroutine calls to close cursors on incomplete
**** subqueries ****/
explainComposite( pParse, p.op, iSub1, iSub2, false );
return SQLITE_OK;
}
#endif
#if !(SQLITE_OMIT_SUBQUERY) || !(SQLITE_OMIT_VIEW)
/* Forward Declarations */
//static void substExprList(sqlite3*, ExprList*, int, ExprList);
//static void substSelect(sqlite3*, Select *, int, ExprList );
/*
** Scan through the expression pExpr. Replace every reference to
** a column in table number iTable with a copy of the iColumn-th
** entry in pEList. (But leave references to the ROWID column
** unchanged.)
**
** This routine is part of the flattening procedure. A subquery
** whose result set is defined by pEList appears as entry in the
** FROM clause of a SELECT such that the VDBE cursor assigned to that
** FORM clause entry is iTable. This routine make the necessary
** changes to pExpr so that it refers directly to the source table
** of the subquery rather the result set of the subquery.
*/
static Expr substExpr(
sqlite3 db, /* Report malloc errors to this connection */
Expr pExpr, /* Expr in which substitution occurs */
int iTable, /* Table to be substituted */
ExprList pEList /* Substitute expressions */
)
{
if ( pExpr == null )
return null;
if ( pExpr.op == TK_COLUMN && pExpr.iTable == iTable )
{
if ( pExpr.iColumn < 0 )
{
pExpr.op = TK_NULL;
}
else
{
Expr pNew;
Debug.Assert( pEList != null && pExpr.iColumn < pEList.nExpr );
Debug.Assert( pExpr.pLeft == null && pExpr.pRight == null );
pNew = sqlite3ExprDup( db, pEList.a[pExpr.iColumn].pExpr, 0 );
if ( pExpr.pColl != null )
{
pNew.pColl = pExpr.pColl;
}
sqlite3ExprDelete( db, ref pExpr );
pExpr = pNew;
}
}
else
{
pExpr.pLeft = substExpr( db, pExpr.pLeft, iTable, pEList );
pExpr.pRight = substExpr( db, pExpr.pRight, iTable, pEList );
if ( ExprHasProperty( pExpr, EP_xIsSelect ) )
{
substSelect( db, pExpr.x.pSelect, iTable, pEList );
}
else
{
substExprList( db, pExpr.x.pList, iTable, pEList );
}
}
return pExpr;
}
static void substExprList(
sqlite3 db, /* Report malloc errors here */
ExprList pList, /* List to scan and in which to make substitutes */
int iTable, /* Table to be substituted */
ExprList pEList /* Substitute values */
)
{
int i;
if ( pList == null )
return;
for ( i = 0; i < pList.nExpr; i++ )
{
pList.a[i].pExpr = substExpr( db, pList.a[i].pExpr, iTable, pEList );
}
}
static void substSelect(
sqlite3 db, /* Report malloc errors here */
Select p, /* SELECT statement in which to make substitutions */
int iTable, /* Table to be replaced */
ExprList pEList /* Substitute values */
)
{
SrcList pSrc;
SrcList_item pItem;
int i;
if ( p == null )
return;
substExprList( db, p.pEList, iTable, pEList );
substExprList( db, p.pGroupBy, iTable, pEList );
substExprList( db, p.pOrderBy, iTable, pEList );
p.pHaving = substExpr( db, p.pHaving, iTable, pEList );
p.pWhere = substExpr( db, p.pWhere, iTable, pEList );
substSelect( db, p.pPrior, iTable, pEList );
pSrc = p.pSrc;
Debug.Assert( pSrc != null ); /* Even for (SELECT 1) we have: pSrc!=0 but pSrc->nSrc==0 */
if ( ALWAYS( pSrc ) )
{
for ( i = pSrc.nSrc; i > 0; i-- )//, pItem++ )
{
pItem = pSrc.a[pSrc.nSrc - i];
substSelect( db, pItem.pSelect, iTable, pEList );
}
}
}
#endif //* !SQLITE_OMIT_SUBQUERY) || !SQLITE_OMIT_VIEW) */
#if !(SQLITE_OMIT_SUBQUERY) || !(SQLITE_OMIT_VIEW)
/*
** This routine attempts to flatten subqueries in order to speed
** execution. It returns 1 if it makes changes and 0 if no flattening
** occurs.
**
** To understand the concept of flattening, consider the following
** query:
**
** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
**
** The default way of implementing this query is to execute the
** subquery first and store the results in a temporary table, then
** run the outer query on that temporary table. This requires two
** passes over the data. Furthermore, because the temporary table
** has no indices, the WHERE clause on the outer query cannot be
** optimized.
**
** This routine attempts to rewrite queries such as the above into
** a single flat select, like this:
**
** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
**
** The code generated for this simpification gives the same result
** but only has to scan the data once. And because indices might
** exist on the table t1, a complete scan of the data might be
** avoided.
**
** Flattening is only attempted if all of the following are true:
**
** (1) The subquery and the outer query do not both use aggregates.
**
** (2) The subquery is not an aggregate or the outer query is not a join.
**
** (3) The subquery is not the right operand of a left outer join
** (Originally ticket #306. Strengthened by ticket #3300)
**
** (4) The subquery is not DISTINCT.
**
** (*) At one point restrictions (4) and (5) defined a subset of DISTINCT
** sub-queries that were excluded from this optimization. Restriction
** (4) has since been expanded to exclude all DISTINCT subqueries.
**
** (6) The subquery does not use aggregates or the outer query is not
** DISTINCT.
**
** (7) The subquery has a FROM clause.
**
** (8) The subquery does not use LIMIT or the outer query is not a join.
**
** (9) The subquery does not use LIMIT or the outer query does not use
** aggregates.
**
** (10) The subquery does not use aggregates or the outer query does not
** use LIMIT.
**
** (11) The subquery and the outer query do not both have ORDER BY clauses.
**
** (*) Not implemented. Subsumed into restriction (3). Was previously
** a separate restriction deriving from ticket #350.
**
** (13) The subquery and outer query do not both use LIMIT.
**
** (14) The subquery does not use OFFSET.
**
** (15) The outer query is not part of a compound select or the
** subquery does not have a LIMIT clause.
** (See ticket #2339 and ticket [02a8e81d44]).
**
** (16) The outer query is not an aggregate or the subquery does
** not contain ORDER BY. (Ticket #2942) This used to not matter
** until we introduced the group_concat() function.
**
** (17) The sub-query is not a compound select, or it is a UNION ALL
** compound clause made up entirely of non-aggregate queries, and
** the parent query:
**
** * is not itself part of a compound select,
** * is not an aggregate or DISTINCT query, and
** * has no other tables or sub-selects in the FROM clause.
**
** The parent and sub-query may contain WHERE clauses. Subject to
** rules (11), (13) and (14), they may also contain ORDER BY,
** LIMIT and OFFSET clauses.
**
** (18) If the sub-query is a compound select, then all terms of the
** ORDER by clause of the parent must be simple references to
** columns of the sub-query.
**
** (19) The subquery does not use LIMIT or the outer query does not
** have a WHERE clause.
**
** (20) If the sub-query is a compound select, then it must not use
** an ORDER BY clause. Ticket #3773. We could relax this constraint
** somewhat by saying that the terms of the ORDER BY clause must
** appear as unmodified result columns in the outer query. But
** have other optimizations in mind to deal with that case.
**
** (21) The subquery does not use LIMIT or the outer query is not
** DISTINCT. (See ticket [752e1646fc]).
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p.pSrc.a[iFrom]. isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
**
** All of the expression analysis must occur on both the outer query and
** the subquery before this routine runs.
*/
static int flattenSubquery(
Parse pParse, /* Parsing context */
Select p, /* The parent or outer SELECT statement */
int iFrom, /* Index in p.pSrc.a[] of the inner subquery */
bool isAgg, /* True if outer SELECT uses aggregate functions */
bool subqueryIsAgg /* True if the subquery uses aggregate functions */
)
{
string zSavedAuthContext = pParse.zAuthContext;
Select pParent;
Select pSub; /* The inner query or "subquery" */
Select pSub1; /* Pointer to the rightmost select in sub-query */
SrcList pSrc; /* The FROM clause of the outer query */
SrcList pSubSrc; /* The FROM clause of the subquery */
ExprList pList; /* The result set of the outer query */
int iParent; /* VDBE cursor number of the pSub result set temp table */
int i; /* Loop counter */
Expr pWhere; /* The WHERE clause */
SrcList_item pSubitem;/* The subquery */
sqlite3 db = pParse.db;
/* Check to see if flattening is permitted. Return 0 if not.
*/
Debug.Assert( p != null );
Debug.Assert( p.pPrior == null ); /* Unable to flatten compound queries */
if ( ( db.flags & SQLITE_QueryFlattener ) != 0 )
return 0;
pSrc = p.pSrc;
Debug.Assert( pSrc != null && iFrom >= 0 && iFrom < pSrc.nSrc );
pSubitem = pSrc.a[iFrom];
iParent = pSubitem.iCursor;
pSub = pSubitem.pSelect;
Debug.Assert( pSub != null );
if ( isAgg && subqueryIsAgg )
return 0; /* Restriction (1) */
if ( subqueryIsAgg && pSrc.nSrc > 1 )
return 0; /* Restriction (2) */
pSubSrc = pSub.pSrc;
Debug.Assert( pSubSrc != null );
/* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET
** because they could be computed at compile-time. But when LIMIT and OFFSET
** became arbitrary expressions, we were forced to add restrictions (13)
** and (14). */
if ( pSub.pLimit != null && p.pLimit != null )
return 0; /* Restriction (13) */
if ( pSub.pOffset != null )
return 0; /* Restriction (14) */
if ( p.pRightmost != null && pSub.pLimit != null )
{
return 0; /* Restriction (15) */
}
if ( pSubSrc.nSrc == 0 )
return 0; /* Restriction (7) */
if ( ( pSub.selFlags & SF_Distinct ) != 0 )
return 0; /* Restriction (5) */
if ( pSub.pLimit != null && ( pSrc.nSrc > 1 || isAgg ) )
{
return 0; /* Restrictions (8)(9) */
}
if ( ( p.selFlags & SF_Distinct ) != 0 && subqueryIsAgg )
{
return 0; /* Restriction (6) */
}
if ( p.pOrderBy != null && pSub.pOrderBy != null )
{
return 0; /* Restriction (11) */
}
if ( isAgg && pSub.pOrderBy != null )
return 0; /* Restriction (16) */
if ( pSub.pLimit != null && p.pWhere != null )
return 0; /* Restriction (19) */
if ( pSub.pLimit != null && ( p.selFlags & SF_Distinct ) != 0 )
{
return 0; /* Restriction (21) */
}
/* OBSOLETE COMMENT 1:
** Restriction 3: If the subquery is a join, make sure the subquery is
** not used as the right operand of an outer join. Examples of why this
** is not allowed:
**
** t1 LEFT OUTER JOIN (t2 JOIN t3)
**
** If we flatten the above, we would get
**
** (t1 LEFT OUTER JOIN t2) JOIN t3
**
** which is not at all the same thing.
**
** OBSOLETE COMMENT 2:
** Restriction 12: If the subquery is the right operand of a left outer
/* Restriction 12: If the subquery is the right operand of a left outer
** join, make sure the subquery has no WHERE clause.
** An examples of why this is not allowed:
**
** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0)
**
** If we flatten the above, we would get
**
** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0
**
** But the t2.x>0 test will always fail on a NULL row of t2, which
** effectively converts the OUTER JOIN into an INNER JOIN.
**
** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE:
** Ticket #3300 shows that flattening the right term of a LEFT JOIN
** is fraught with danger. Best to avoid the whole thing. If the
** subquery is the right term of a LEFT JOIN, then do not flatten.
*/
if ( ( pSubitem.jointype & JT_OUTER ) != 0 )
{
return 0;
}
/* Restriction 17: If the sub-query is a compound SELECT, then it must
** use only the UNION ALL operator. And none of the simple select queries
** that make up the compound SELECT are allowed to be aggregate or distinct
** queries.
*/
if ( pSub.pPrior != null )
{
if ( pSub.pOrderBy != null )
{
return 0; /* Restriction 20 */
}
if ( isAgg || ( p.selFlags & SF_Distinct ) != 0 || pSrc.nSrc != 1 )
{
return 0;
}
for ( pSub1 = pSub; pSub1 != null; pSub1 = pSub1.pPrior )
{
testcase( ( pSub1.selFlags & ( SF_Distinct | SF_Aggregate ) ) == SF_Distinct );
testcase( ( pSub1.selFlags & ( SF_Distinct | SF_Aggregate ) ) == SF_Aggregate );
if ( ( pSub1.selFlags & ( SF_Distinct | SF_Aggregate ) ) != 0
|| ( pSub1.pPrior != null && pSub1.op != TK_ALL )
|| NEVER( pSub1.pSrc == null ) || pSub1.pSrc.nSrc != 1
)
{
return 0;
}
}
/* Restriction 18. */
if ( p.pOrderBy != null )
{
int ii;
for ( ii = 0; ii < p.pOrderBy.nExpr; ii++ )
{
if ( p.pOrderBy.a[ii].iCol == 0 )
return 0;
}
}
}
/***** If we reach this point, flattening is permitted. *****/
/* Authorize the subquery */
pParse.zAuthContext = pSubitem.zName;
sqlite3AuthCheck( pParse, SQLITE_SELECT, null, null, null );
pParse.zAuthContext = zSavedAuthContext;
/* If the sub-query is a compound SELECT statement, then (by restrictions
** 17 and 18 above) it must be a UNION ALL and the parent query must
** be of the form:
**
** SELECT <expr-list> FROM (<sub-query>) <where-clause>
**
** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
** creates N-1 copies of the parent query without any ORDER BY, LIMIT or
** OFFSET clauses and joins them to the left-hand-side of the original
** using UNION ALL operators. In this case N is the number of simple
** select statements in the compound sub-query.
**
** Example:
**
** SELECT a+1 FROM (
** SELECT x FROM tab
** UNION ALL
** SELECT y FROM tab
** UNION ALL
** SELECT abs(z*2) FROM tab2
** ) WHERE a!=5 ORDER BY 1
**
** Transformed into:
**
** SELECT x+1 FROM tab WHERE x+1!=5
** UNION ALL
** SELECT y+1 FROM tab WHERE y+1!=5
** UNION ALL
** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5
** ORDER BY 1
**
** We call this the "compound-subquery flattening".
*/
for ( pSub = pSub.pPrior; pSub != null; pSub = pSub.pPrior )
{
Select pNew;
ExprList pOrderBy = p.pOrderBy;
Expr pLimit = p.pLimit;
Select pPrior = p.pPrior;
p.pOrderBy = null;
p.pSrc = null;
p.pPrior = null;
p.pLimit = null;
pNew = sqlite3SelectDup( db, p, 0 );
p.pLimit = pLimit;
p.pOrderBy = pOrderBy;
p.pSrc = pSrc;
p.op = TK_ALL;
p.pRightmost = null;
if ( pNew == null )
{
pNew = pPrior;
}
else
{
pNew.pPrior = pPrior;
pNew.pRightmost = null;
}
p.pPrior = pNew;
// if ( db.mallocFailed != 0 ) return 1;
}
/* Begin flattening the iFrom-th entry of the FROM clause
** in the outer query.
*/
pSub = pSub1 = pSubitem.pSelect;
/* Delete the transient table structure associated with the
** subquery
*/
sqlite3DbFree( db, ref pSubitem.zDatabase );
sqlite3DbFree( db, ref pSubitem.zName );
sqlite3DbFree( db, ref pSubitem.zAlias );
pSubitem.zDatabase = null;
pSubitem.zName = null;
pSubitem.zAlias = null;
pSubitem.pSelect = null;
/* Defer deleting the Table object associated with the
** subquery until code generation is
** complete, since there may still exist Expr.pTab entries that
** refer to the subquery even after flattening. Ticket #3346.
**
** pSubitem->pTab is always non-NULL by test restrictions and tests above.
*/
if ( ALWAYS( pSubitem.pTab != null ) )
{
Table pTabToDel = pSubitem.pTab;
if ( pTabToDel.nRef == 1 )
{
Parse pToplevel = sqlite3ParseToplevel( pParse );
pTabToDel.pNextZombie = pToplevel.pZombieTab;
pToplevel.pZombieTab = pTabToDel;
}
else
{
pTabToDel.nRef--;
}
pSubitem.pTab = null;
}
/* The following loop runs once for each term in a compound-subquery
** flattening (as described above). If we are doing a different kind
** of flattening - a flattening other than a compound-subquery flattening -
** then this loop only runs once.
**
** This loop moves all of the FROM elements of the subquery into the
** the FROM clause of the outer query. Before doing this, remember
** the cursor number for the original outer query FROM element in
** iParent. The iParent cursor will never be used. Subsequent code
** will scan expressions looking for iParent references and replace
** those references with expressions that resolve to the subquery FROM
** elements we are now copying in.
*/
for ( pParent = p; pParent != null; pParent = pParent.pPrior, pSub = pSub.pPrior )
{
int nSubSrc;
u8 jointype = 0;
pSubSrc = pSub.pSrc; /* FROM clause of subquery */
nSubSrc = pSubSrc.nSrc; /* Number of terms in subquery FROM clause */
pSrc = pParent.pSrc; /* FROM clause of the outer query */
if ( pSrc != null )
{
Debug.Assert( pParent == p ); /* First time through the loop */
jointype = pSubitem.jointype;
}
else
{
Debug.Assert( pParent != p ); /* 2nd and subsequent times through the loop */
pSrc = pParent.pSrc = sqlite3SrcListAppend( db, null, null, null );
//if ( pSrc == null )
//{
// //Debug.Assert( db.mallocFailed != 0 );
// break;
//}
}
/* The subquery uses a single slot of the FROM clause of the outer
** query. If the subquery has more than one element in its FROM clause,
** then expand the outer query to make space for it to hold all elements
** of the subquery.
**
** Example:
**
** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
**
** The outer query has 3 slots in its FROM clause. One slot of the
** outer query (the middle slot) is used by the subquery. The next
** block of code will expand the out query to 4 slots. The middle
** slot is expanded to two slots in order to make space for the
** two elements in the FROM clause of the subquery.
*/
if ( nSubSrc > 1 )
{
pParent.pSrc = pSrc = sqlite3SrcListEnlarge( db, pSrc, nSubSrc - 1, iFrom + 1 );
//if ( db.mallocFailed != 0 )
//{
// break;
//}
}
/* Transfer the FROM clause terms from the subquery into the
** outer query.
*/
for ( i = 0; i < nSubSrc; i++ )
{
sqlite3IdListDelete( db, ref pSrc.a[i + iFrom].pUsing );
pSrc.a[i + iFrom] = pSubSrc.a[i];
pSubSrc.a[i] = new SrcList_item();//memset(pSubSrc.a[i], 0, sizeof(pSubSrc.a[i]));
}
pSubitem = pSrc.a[iFrom]; // Reset for C#
pSrc.a[iFrom].jointype = jointype;
/* Now begin substituting subquery result set expressions for
** references to the iParent in the outer query.
**
** Example:
**
** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
** \ \_____________ subquery __________/ /
** \_____________________ outer query ______________________________/
**
** We look at every expression in the outer query and every place we see
** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
*/
pList = pParent.pEList;
for ( i = 0; i < pList.nExpr; i++ )
{
if ( pList.a[i].zName == null )
{
string zSpan = pList.a[i].zSpan;
if ( ALWAYS( zSpan ) )
{
pList.a[i].zName = zSpan;// sqlite3DbStrDup( db, zSpan );
}
}
}
substExprList( db, pParent.pEList, iParent, pSub.pEList );
if ( isAgg )
{
substExprList( db, pParent.pGroupBy, iParent, pSub.pEList );
pParent.pHaving = substExpr( db, pParent.pHaving, iParent, pSub.pEList );
}
if ( pSub.pOrderBy != null )
{
Debug.Assert( pParent.pOrderBy == null );
pParent.pOrderBy = pSub.pOrderBy;
pSub.pOrderBy = null;
}
else if ( pParent.pOrderBy != null )
{
substExprList( db, pParent.pOrderBy, iParent, pSub.pEList );
}
if ( pSub.pWhere != null )
{
pWhere = sqlite3ExprDup( db, pSub.pWhere, 0 );
}
else
{
pWhere = null;
}
if ( subqueryIsAgg )
{
Debug.Assert( pParent.pHaving == null );
pParent.pHaving = pParent.pWhere;
pParent.pWhere = pWhere;
pParent.pHaving = substExpr( db, pParent.pHaving, iParent, pSub.pEList );
pParent.pHaving = sqlite3ExprAnd( db, pParent.pHaving,
sqlite3ExprDup( db, pSub.pHaving, 0 ) );
Debug.Assert( pParent.pGroupBy == null );
pParent.pGroupBy = sqlite3ExprListDup( db, pSub.pGroupBy, 0 );
}
else
{
pParent.pWhere = substExpr( db, pParent.pWhere, iParent, pSub.pEList );
pParent.pWhere = sqlite3ExprAnd( db, pParent.pWhere, pWhere );
}
/* The flattened query is distinct if either the inner or the
** outer query is distinct.
*/
pParent.selFlags = (u16)( pParent.selFlags | pSub.selFlags & SF_Distinct );
/*
** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
**
** One is tempted to try to add a and b to combine the limits. But this
** does not work if either limit is negative.
*/
if ( pSub.pLimit != null )
{
pParent.pLimit = pSub.pLimit;
pSub.pLimit = null;
}
}
/* Finially, delete what is left of the subquery and return
** success.
*/
sqlite3SelectDelete( db, ref pSub );
sqlite3SelectDelete( db, ref pSub1 );
return 1;
}
#endif //* !SQLITE_OMIT_SUBQUERY) || !SQLITE_OMIT_VIEW) */
/*
** Analyze the SELECT statement passed as an argument to see if it
** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if
** it is, or 0 otherwise. At present, a query is considered to be
** a min()/max() query if:
**
** 1. There is a single object in the FROM clause.
**
** 2. There is a single expression in the result set, and it is
** either min(x) or max(x), where x is a column reference.
*/
static u8 minMaxQuery( Select p )
{
Expr pExpr;
ExprList pEList = p.pEList;
if ( pEList.nExpr != 1 )
return WHERE_ORDERBY_NORMAL;
pExpr = pEList.a[0].pExpr;
if ( pExpr.op != TK_AGG_FUNCTION )
return 0;
if ( NEVER( ExprHasProperty( pExpr, EP_xIsSelect ) ) )
return 0;
pEList = pExpr.x.pList;
if ( pEList == null || pEList.nExpr != 1 )
return 0;
if ( pEList.a[0].pExpr.op != TK_AGG_COLUMN )
return WHERE_ORDERBY_NORMAL;
Debug.Assert( !ExprHasProperty( pExpr, EP_IntValue ) );
if ( pExpr.u.zToken.Equals( "min", StringComparison.OrdinalIgnoreCase ) )
{
return WHERE_ORDERBY_MIN;
}
else if ( pExpr.u.zToken.Equals( "max", StringComparison.OrdinalIgnoreCase ) )
{
return WHERE_ORDERBY_MAX;
}
return WHERE_ORDERBY_NORMAL;
}
/*
** The select statement passed as the first argument is an aggregate query.
** The second argment is the associated aggregate-info object. This
** function tests if the SELECT is of the form:
**
** SELECT count() FROM <tbl>
**
** where table is a database table, not a sub-select or view. If the query
** does match this pattern, then a pointer to the Table object representing
** <tbl> is returned. Otherwise, 0 is returned.
*/
static Table isSimpleCount( Select p, AggInfo pAggInfo )
{
Table pTab;
Expr pExpr;
Debug.Assert( null == p.pGroupBy );
if ( p.pWhere != null || p.pEList.nExpr != 1
|| p.pSrc.nSrc != 1 || p.pSrc.a[0].pSelect != null
)
{
return null;
}
pTab = p.pSrc.a[0].pTab;
pExpr = p.pEList.a[0].pExpr;
Debug.Assert( pTab != null && null == pTab.pSelect && pExpr != null );
if ( IsVirtual( pTab ) )
return null;
if ( pExpr.op != TK_AGG_FUNCTION )
return null;
if ( ( pAggInfo.aFunc[0].pFunc.flags & SQLITE_FUNC_COUNT ) == 0 )
return null;
if ( ( pExpr.flags & EP_Distinct ) != 0 )
return null;
return pTab;
}
/*
** If the source-list item passed as an argument was augmented with an
** INDEXED BY clause, then try to locate the specified index. If there
** was such a clause and the named index cannot be found, return
** SQLITE_ERROR and leave an error in pParse. Otherwise, populate
** pFrom.pIndex and return SQLITE_OK.
*/
static int sqlite3IndexedByLookup( Parse pParse, SrcList_item pFrom )
{
if ( pFrom.pTab != null && pFrom.zIndex != null && pFrom.zIndex.Length != 0 )
{
Table pTab = pFrom.pTab;
string zIndex = pFrom.zIndex;
Index pIdx;
for ( pIdx = pTab.pIndex;
pIdx != null && !pIdx.zName.Equals( zIndex, StringComparison.OrdinalIgnoreCase );
pIdx = pIdx.pNext
)
;
if ( null == pIdx )
{
sqlite3ErrorMsg( pParse, "no such index: %s", zIndex );
pParse.checkSchema = 1;
return SQLITE_ERROR;
}
pFrom.pIndex = pIdx;
}
return SQLITE_OK;
}
/*
** This routine is a Walker callback for "expanding" a SELECT statement.
** "Expanding" means to do the following:
**
** (1) Make sure VDBE cursor numbers have been assigned to every
** element of the FROM clause.
**
** (2) Fill in the pTabList.a[].pTab fields in the SrcList that
** defines FROM clause. When views appear in the FROM clause,
** fill pTabList.a[].x.pSelect with a copy of the SELECT statement
** that implements the view. A copy is made of the view's SELECT
** statement so that we can freely modify or delete that statement
** without worrying about messing up the presistent representation
** of the view.
**
** (3) Add terms to the WHERE clause to accomodate the NATURAL keyword
** on joins and the ON and USING clause of joins.
**
** (4) Scan the list of columns in the result set (pEList) looking
** for instances of the "*" operator or the TABLE.* operator.
** If found, expand each "*" to be every column in every table
** and TABLE.* to be every column in TABLE.
**
*/
static int selectExpander( Walker pWalker, Select p )
{
Parse pParse = pWalker.pParse;
int i, j, k;
SrcList pTabList;
ExprList pEList;
SrcList_item pFrom;
sqlite3 db = pParse.db;
//if ( db.mallocFailed != 0 )
//{
// return WRC_Abort;
//}
if ( NEVER( p.pSrc == null ) || ( p.selFlags & SF_Expanded ) != 0 )
{
return WRC_Prune;
}
p.selFlags |= SF_Expanded;
pTabList = p.pSrc;
pEList = p.pEList;
/* Make sure cursor numbers have been assigned to all entries in
** the FROM clause of the SELECT statement.
*/
sqlite3SrcListAssignCursors( pParse, pTabList );
/* Look up every table named in the FROM clause of the select. If
** an entry of the FROM clause is a subquery instead of a table or view,
** then create a transient table ure to describe the subquery.
*/
for ( i = 0; i < pTabList.nSrc; i++ )// pFrom++ )
{
pFrom = pTabList.a[i];
Table pTab;
if ( pFrom.pTab != null )
{
/* This statement has already been prepared. There is no need
** to go further. */
Debug.Assert( i == 0 );
return WRC_Prune;
}
if ( pFrom.zName == null )
{
#if !SQLITE_OMIT_SUBQUERY
Select pSel = pFrom.pSelect;
/* A sub-query in the FROM clause of a SELECT */
Debug.Assert( pSel != null );
Debug.Assert( pFrom.pTab == null );
sqlite3WalkSelect( pWalker, pSel );
pFrom.pTab = pTab = new Table();// sqlite3DbMallocZero( db, sizeof( Table ) );
if ( pTab == null )
return WRC_Abort;
pTab.nRef = 1;
pTab.zName = sqlite3MPrintf( db, "sqlite_subquery_%p_", pTab );
while ( pSel.pPrior != null )
{
pSel = pSel.pPrior;
}
selectColumnsFromExprList( pParse, pSel.pEList, ref pTab.nCol, ref pTab.aCol );
pTab.iPKey = -1;
pTab.nRowEst = 1000000;
pTab.tabFlags |= TF_Ephemeral;
#endif
}
else
{
/* An ordinary table or view name in the FROM clause */
Debug.Assert( pFrom.pTab == null );
pFrom.pTab = pTab =
sqlite3LocateTable( pParse, 0, pFrom.zName, pFrom.zDatabase );
if ( pTab == null )
return WRC_Abort;
pTab.nRef++;
#if !(SQLITE_OMIT_VIEW) || !(SQLITE_OMIT_VIRTUALTABLE)
if ( pTab.pSelect != null || IsVirtual( pTab ) )
{
/* We reach here if the named table is a really a view */
if ( sqlite3ViewGetColumnNames( pParse, pTab ) != 0 )
return WRC_Abort;
pFrom.pSelect = sqlite3SelectDup( db, pTab.pSelect, 0 );
sqlite3WalkSelect( pWalker, pFrom.pSelect );
}
#endif
}
/* Locate the index named by the INDEXED BY clause, if any. */
if ( sqlite3IndexedByLookup( pParse, pFrom ) != 0 )
{
return WRC_Abort;
}
}
/* Process NATURAL keywords, and ON and USING clauses of joins.
*/
if ( /* db.mallocFailed != 0 || */ sqliteProcessJoin( pParse, p ) != 0 )
{
return WRC_Abort;
}
/* For every "*" that occurs in the column list, insert the names of
** all columns in all tables. And for every TABLE.* insert the names
** of all columns in TABLE. The parser inserted a special expression
** with the TK_ALL operator for each "*" that it found in the column list.
** The following code just has to locate the TK_ALL expressions and expand
** each one to the list of all columns in all tables.
**
** The first loop just checks to see if there are any "*" operators
** that need expanding.
*/
for ( k = 0; k < pEList.nExpr; k++ )
{
Expr pE = pEList.a[k].pExpr;
if ( pE.op == TK_ALL )
break;
Debug.Assert( pE.op != TK_DOT || pE.pRight != null );
Debug.Assert( pE.op != TK_DOT || ( pE.pLeft != null && pE.pLeft.op == TK_ID ) );
if ( pE.op == TK_DOT && pE.pRight.op == TK_ALL )
break;
}
if ( k < pEList.nExpr )
{
/*
** If we get here it means the result set contains one or more "*"
** operators that need to be expanded. Loop through each expression
** in the result set and expand them one by one.
*/
ExprList_item[] a = pEList.a;
ExprList pNew = null;
int flags = pParse.db.flags;
bool longNames = ( flags & SQLITE_FullColNames ) != 0
&& ( flags & SQLITE_ShortColNames ) == 0;
for ( k = 0; k < pEList.nExpr; k++ )
{
Expr pE = a[k].pExpr;
Debug.Assert( pE.op != TK_DOT || pE.pRight != null );
if ( pE.op != TK_ALL && ( pE.op != TK_DOT || pE.pRight.op != TK_ALL ) )
{
/* This particular expression does not need to be expanded.
*/
pNew = sqlite3ExprListAppend( pParse, pNew, a[k].pExpr );
if ( pNew != null )
{
pNew.a[pNew.nExpr - 1].zName = a[k].zName;
pNew.a[pNew.nExpr - 1].zSpan = a[k].zSpan;
a[k].zName = null;
a[k].zSpan = null;
}
a[k].pExpr = null;
}
else
{
/* This expression is a "*" or a "TABLE.*" and needs to be
** expanded. */
int tableSeen = 0; /* Set to 1 when TABLE matches */
string zTName; /* text of name of TABLE */
if ( pE.op == TK_DOT )
{
Debug.Assert( pE.pLeft != null );
Debug.Assert( !ExprHasProperty( pE.pLeft, EP_IntValue ) );
zTName = pE.pLeft.u.zToken;
}
else
{
zTName = null;
}
for ( i = 0; i < pTabList.nSrc; i++ )//, pFrom++ )
{
pFrom = pTabList.a[i];
Table pTab = pFrom.pTab;
string zTabName = pFrom.zAlias;
if ( zTabName == null )
{
zTabName = pTab.zName;
}
///if ( db.mallocFailed != 0 ) break;
if ( zTName != null && !zTName.Equals( zTabName, StringComparison.OrdinalIgnoreCase ) )
{
continue;
}
tableSeen = 1;
for ( j = 0; j < pTab.nCol; j++ )
{
Expr pExpr, pRight;
string zName = pTab.aCol[j].zName;
string zColname; /* The computed column name */
string zToFree; /* Malloced string that needs to be freed */
Token sColname = new Token(); /* Computed column name as a token */
/* If a column is marked as 'hidden' (currently only possible
** for virtual tables), do not include it in the expanded
** result-set list.
*/
if ( IsHiddenColumn( pTab.aCol[j] ) )
{
Debug.Assert( IsVirtual( pTab ) );
continue;
}
if ( i > 0 && ( zTName == null || zTName.Length == 0 ) )
{
int iDummy = 0;
if ( ( pFrom.jointype & JT_NATURAL ) != 0
&& tableAndColumnIndex( pTabList, i, zName, ref iDummy, ref iDummy ) != 0
)
{
/* In a NATURAL join, omit the join columns from the
** table to the right of the join */
continue;
}
if ( sqlite3IdListIndex( pFrom.pUsing, zName ) >= 0 )
{
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;
}
}
pRight = sqlite3Expr( db, TK_ID, zName );
zColname = zName;
zToFree = string.Empty;
if ( longNames || pTabList.nSrc > 1 )
{
Expr pLeft;
pLeft = sqlite3Expr( db, TK_ID, zTabName );
pExpr = sqlite3PExpr( pParse, TK_DOT, pLeft, pRight, 0 );
if ( longNames )
{
zColname = sqlite3MPrintf( db, "%s.%s", zTabName, zName );
zToFree = zColname;
}
}
else
{
pExpr = pRight;
}
pNew = sqlite3ExprListAppend( pParse, pNew, pExpr );
sColname.z = zColname;
sColname.n = sqlite3Strlen30( zColname );
sqlite3ExprListSetName( pParse, pNew, sColname, 0 );
sqlite3DbFree( db, ref zToFree );
}
}
if ( tableSeen == 0 )
{
if ( zTName != null )
{
sqlite3ErrorMsg( pParse, "no such table: %s", zTName );
}
else
{
sqlite3ErrorMsg( pParse, "no tables specified" );
}
}
}
}
sqlite3ExprListDelete( db, ref pEList );
p.pEList = pNew;
}
//#if SQLITE_MAX_COLUMN
if ( p.pEList != null && p.pEList.nExpr > db.aLimit[SQLITE_LIMIT_COLUMN] )
{
sqlite3ErrorMsg( pParse, "too many columns in result set" );
}
//#endif
return WRC_Continue;
}
/*
** No-op routine for the parse-tree walker.
**
** When this routine is the Walker.xExprCallback then expression trees
** are walked without any actions being taken at each node. Presumably,
** when this routine is used for Walker.xExprCallback then
** Walker.xSelectCallback is set to do something useful for every
** subquery in the parser tree.
*/
static int exprWalkNoop( Walker NotUsed, ref Expr NotUsed2 )
{
UNUSED_PARAMETER2( NotUsed, NotUsed2 );
return WRC_Continue;
}
/*
** This routine "expands" a SELECT statement and all of its subqueries.
** For additional information on what it means to "expand" a SELECT
** statement, see the comment on the selectExpand worker callback above.
**
** Expanding a SELECT statement is the first step in processing a
** SELECT statement. The SELECT statement must be expanded before
** name resolution is performed.
**
** If anything goes wrong, an error message is written into pParse.
** The calling function can detect the problem by looking at pParse.nErr
** and/or pParse.db.mallocFailed.
*/
static void sqlite3SelectExpand( Parse pParse, Select pSelect )
{
Walker w = new Walker();
w.xSelectCallback = selectExpander;
w.xExprCallback = exprWalkNoop;
w.pParse = pParse;
sqlite3WalkSelect( w, pSelect );
}
#if !SQLITE_OMIT_SUBQUERY
/*
** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
** interface.
**
** For each FROM-clause subquery, add Column.zType and Column.zColl
** information to the Table ure that represents the result set
** of that subquery.
**
** The Table ure that represents the result set was coned
** by selectExpander() but the type and collation information was omitted
** at that point because identifiers had not yet been resolved. This
** routine is called after identifier resolution.
*/
static int selectAddSubqueryTypeInfo( Walker pWalker, Select p )
{
Parse pParse;
int i;
SrcList pTabList;
SrcList_item pFrom;
Debug.Assert( ( p.selFlags & SF_Resolved ) != 0 );
if ( ( p.selFlags & SF_HasTypeInfo ) == 0 )
{
p.selFlags |= SF_HasTypeInfo;
pParse = pWalker.pParse;
pTabList = p.pSrc;
for ( i = 0; i < pTabList.nSrc; i++ )//, pFrom++ )
{
pFrom = pTabList.a[i];
Table pTab = pFrom.pTab;
if ( ALWAYS( pTab != null ) && ( pTab.tabFlags & TF_Ephemeral ) != 0 )
{
/* A sub-query in the FROM clause of a SELECT */
Select pSel = pFrom.pSelect;
Debug.Assert( pSel != null );
while ( pSel.pPrior != null )
pSel = pSel.pPrior;
selectAddColumnTypeAndCollation( pParse, pTab.nCol, pTab.aCol, pSel );
}
}
}
return WRC_Continue;
}
#endif
/*
** This routine adds datatype and collating sequence information to
** the Table ures of all FROM-clause subqueries in a
** SELECT statement.
**
** Use this routine after name resolution.
*/
static void sqlite3SelectAddTypeInfo( Parse pParse, Select pSelect )
{
#if !SQLITE_OMIT_SUBQUERY
Walker w = new Walker();
w.xSelectCallback = selectAddSubqueryTypeInfo;
w.xExprCallback = exprWalkNoop;
w.pParse = pParse;
sqlite3WalkSelect( w, pSelect );
#endif
}
/*
** This routine sets of a SELECT statement for processing. The
** following is accomplished:
**
** * VDBE VdbeCursor numbers are assigned to all FROM-clause terms.
** * Ephemeral Table objects are created for all FROM-clause subqueries.
** * ON and USING clauses are shifted into WHERE statements
** * Wildcards "*" and "TABLE.*" in result sets are expanded.
** * Identifiers in expression are matched to tables.
**
** This routine acts recursively on all subqueries within the SELECT.
*/
static void sqlite3SelectPrep(
Parse pParse, /* The parser context */
Select p, /* The SELECT statement being coded. */
NameContext pOuterNC /* Name context for container */
)
{
if ( NEVER( p == null ) )
return;
////sqlite3 db = pParse.db;
if ( ( p.selFlags & SF_HasTypeInfo ) != 0 )
return;
sqlite3SelectExpand( pParse, p );
if ( pParse.nErr != 0 /*|| db.mallocFailed != 0 */ )
return;
sqlite3ResolveSelectNames( pParse, p, pOuterNC );
if ( pParse.nErr != 0 /*|| db.mallocFailed != 0 */ )
return;
sqlite3SelectAddTypeInfo( pParse, p );
}
/*
** Reset the aggregate accumulator.
**
** The aggregate accumulator is a set of memory cells that hold
** intermediate results while calculating an aggregate. This
** routine simply stores NULLs in all of those memory cells.
*/
static void resetAccumulator( Parse pParse, AggInfo pAggInfo )
{
Vdbe v = pParse.pVdbe;
int i;
AggInfo_func pFunc;
if ( pAggInfo.nFunc + pAggInfo.nColumn == 0 )
{
return;
}
for ( i = 0; i < pAggInfo.nColumn; i++ )
{
sqlite3VdbeAddOp2( v, OP_Null, 0, pAggInfo.aCol[i].iMem );
}
for ( i = 0; i < pAggInfo.nFunc; i++ )
{//, pFunc++){
pFunc = pAggInfo.aFunc[i];
sqlite3VdbeAddOp2( v, OP_Null, 0, pFunc.iMem );
if ( pFunc.iDistinct >= 0 )
{
Expr pE = pFunc.pExpr;
Debug.Assert( !ExprHasProperty( pE, EP_xIsSelect ) );
if ( pE.x.pList == null || pE.x.pList.nExpr != 1 )
{
sqlite3ErrorMsg( pParse, "DISTINCT aggregates must have exactly one " +
"argument" );
pFunc.iDistinct = -1;
}
else
{
KeyInfo pKeyInfo = keyInfoFromExprList( pParse, pE.x.pList );
sqlite3VdbeAddOp4( v, OP_OpenEphemeral, pFunc.iDistinct, 0, 0,
pKeyInfo, P4_KEYINFO_HANDOFF );
}
}
}
}
/*
** Invoke the OP_AggFinalize opcode for every aggregate function
** in the AggInfo structure.
*/
static void finalizeAggFunctions( Parse pParse, AggInfo pAggInfo )
{
Vdbe v = pParse.pVdbe;
int i;
AggInfo_func pF;
for ( i = 0; i < pAggInfo.nFunc; i++ )
{//, pF++){
pF = pAggInfo.aFunc[i];
ExprList pList = pF.pExpr.x.pList;
Debug.Assert( !ExprHasProperty( pF.pExpr, EP_xIsSelect ) );
sqlite3VdbeAddOp4( v, OP_AggFinal, pF.iMem, pList != null ? pList.nExpr : 0, 0,
pF.pFunc, P4_FUNCDEF );
}
}
/*
** Update the accumulator memory cells for an aggregate based on
** the current cursor position.
*/
static void updateAccumulator( Parse pParse, AggInfo pAggInfo )
{
Vdbe v = pParse.pVdbe;
int i;
AggInfo_func pF;
AggInfo_col pC;
pAggInfo.directMode = 1;
sqlite3ExprCacheClear( pParse );
for ( i = 0; i < pAggInfo.nFunc; i++ )
{//, pF++){
pF = pAggInfo.aFunc[i];
int nArg;
int addrNext = 0;
int regAgg;
Debug.Assert( !ExprHasProperty( pF.pExpr, EP_xIsSelect ) );
ExprList pList = pF.pExpr.x.pList;
if ( pList != null )
{
nArg = pList.nExpr;
regAgg = sqlite3GetTempRange( pParse, nArg );
sqlite3ExprCodeExprList( pParse, pList, regAgg, true );
}
else
{
nArg = 0;
regAgg = 0;
}
if ( pF.iDistinct >= 0 )
{
addrNext = sqlite3VdbeMakeLabel( v );
Debug.Assert( nArg == 1 );
codeDistinct( pParse, pF.iDistinct, addrNext, 1, regAgg );
}
if ( ( pF.pFunc.flags & SQLITE_FUNC_NEEDCOLL ) != 0 )
{
CollSeq pColl = null;
ExprList_item pItem;
int j;
Debug.Assert( pList != null ); /* pList!=0 if pF->pFunc has NEEDCOLL */
for ( j = 0; pColl == null && j < nArg; j++ )
{//, pItem++){
pItem = pList.a[j];
pColl = sqlite3ExprCollSeq( pParse, pItem.pExpr );
}
if ( pColl == null )
{
pColl = pParse.db.pDfltColl;
}
sqlite3VdbeAddOp4( v, OP_CollSeq, 0, 0, 0, pColl, P4_COLLSEQ );
}
sqlite3VdbeAddOp4( v, OP_AggStep, 0, regAgg, pF.iMem,
pF.pFunc, P4_FUNCDEF );
sqlite3VdbeChangeP5( v, (u8)nArg );
sqlite3ExprCacheAffinityChange( pParse, regAgg, nArg );
sqlite3ReleaseTempRange( pParse, regAgg, nArg );
if ( addrNext != 0 )
{
sqlite3VdbeResolveLabel( v, addrNext );
sqlite3ExprCacheClear( pParse );
}
}
/* Before populating the accumulator registers, clear the column cache.
** Otherwise, if any of the required column values are already present
** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value
** to pC->iMem. But by the time the value is used, the original register
** may have been used, invalidating the underlying buffer holding the
** text or blob value. See ticket [883034dcb5].
**
** Another solution would be to change the OP_SCopy used to copy cached
** values to an OP_Copy.
*/
sqlite3ExprCacheClear( pParse );
for ( i = 0; i < pAggInfo.nAccumulator; i++ )//, pC++)
{
pC = pAggInfo.aCol[i];
sqlite3ExprCode( pParse, pC.pExpr, pC.iMem );
}
pAggInfo.directMode = 0;
sqlite3ExprCacheClear( pParse );
}
/*
** Add a single OP_Explain instruction to the VDBE to explain a simple
** count() query ("SELECT count() FROM pTab").
*/
#if !SQLITE_OMIT_EXPLAIN
static void explainSimpleCount(
Parse pParse, /* Parse context */
Table pTab, /* Table being queried */
Index pIdx /* Index used to optimize scan, or NULL */
)
{
if ( pParse.explain == 2 )
{
string zEqp = sqlite3MPrintf( pParse.db, "SCAN TABLE %s %s%s(~%d rows)",
pTab.zName,
pIdx != null ? "USING COVERING INDEX " : string.Empty,
pIdx != null ? pIdx.zName : string.Empty,
pTab.nRowEst
);
sqlite3VdbeAddOp4(
pParse.pVdbe, OP_Explain, pParse.iSelectId, 0, 0, zEqp, P4_DYNAMIC
);
}
}
#else
//# define explainSimpleCount(a,b,c)
static void explainSimpleCount(Parse a, Table b, Index c){}
#endif
/*
** Generate code for the SELECT statement given in the p argument.
**
** The results are distributed in various ways depending on the
** contents of the SelectDest structure pointed to by argument pDest
** as follows:
**
** pDest.eDest Result
** ------------ -------------------------------------------
** SRT_Output Generate a row of output (using the OP_ResultRow
** opcode) for each row in the result set.
**
** SRT_Mem Only valid if the result is a single column.
** Store the first column of the first result row
** in register pDest.iParm then abandon the rest
** of the query. This destination implies "LIMIT 1".
**
** SRT_Set The result must be a single column. Store each
** row of result as the key in table pDest.iParm.
** Apply the affinity pDest.affinity before storing
** results. Used to implement "IN (SELECT ...)".
**
** SRT_Union Store results as a key in a temporary table pDest.iParm.
**
** SRT_Except Remove results from the temporary table pDest.iParm.
**
** SRT_Table Store results in temporary table pDest.iParm.
** This is like SRT_EphemTab except that the table
** is assumed to already be open.
**
** SRT_EphemTab Create an temporary table pDest.iParm and store
** the result there. The cursor is left open after
** returning. This is like SRT_Table except that
** this destination uses OP_OpenEphemeral to create
** the table first.
**
** SRT_Coroutine Generate a co-routine that returns a new row of
** results each time it is invoked. The entry point
** of the co-routine is stored in register pDest.iParm.
**
** SRT_Exists Store a 1 in memory cell pDest.iParm if the result
** set is not empty.
**
** SRT_Discard Throw the results away. This is used by SELECT
** statements within triggers whose only purpose is
** the side-effects of functions.
**
** This routine returns the number of errors. If any errors are
** encountered, then an appropriate error message is left in
** pParse.zErrMsg.
**
** This routine does NOT free the Select structure passed in. The
** calling function needs to do that.
*/
static SelectDest sdDummy = null;
static bool bDummy = false;
static int sqlite3Select(
Parse pParse, /* The parser context */
Select p, /* The SELECT statement being coded. */
ref SelectDest pDest /* What to do with the query results */
)
{
int i, j; /* Loop counters */
WhereInfo pWInfo; /* Return from sqlite3WhereBegin() */
Vdbe v; /* The virtual machine under construction */
bool isAgg; /* True for select lists like "count()" */
ExprList pEList = new ExprList(); /* List of columns to extract. */
SrcList pTabList = new SrcList(); /* List of tables to select from */
Expr pWhere; /* The WHERE clause. May be NULL */
ExprList pOrderBy; /* The ORDER BY clause. May be NULL */
ExprList pGroupBy; /* The GROUP BY clause. May be NULL */
Expr pHaving; /* The HAVING clause. May be NULL */
bool isDistinct; /* True if the DISTINCT keyword is present */
int distinct; /* Table to use for the distinct set */
int rc = 1; /* Value to return from this function */
int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */
AggInfo sAggInfo; /* Information used by aggregate queries */
int iEnd; /* Address of the end of the query */
sqlite3 db; /* The database connection */
#if !SQLITE_OMIT_EXPLAIN
int iRestoreSelectId = pParse.iSelectId;
pParse.iSelectId = pParse.iNextSelectId++;
#endif
db = pParse.db;
if ( p == null /*|| db.mallocFailed != 0 */ || pParse.nErr != 0 )
{
return 1;
}
#if !SQLITE_OMIT_AUTHORIZATION
if (sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0)) return 1;
#endif
sAggInfo = new AggInfo();// memset(sAggInfo, 0, sAggInfo).Length;
if ( pDest.eDest <= SRT_Discard ) //IgnorableOrderby(pDest))
{
Debug.Assert( pDest.eDest == SRT_Exists || pDest.eDest == SRT_Union ||
pDest.eDest == SRT_Except || pDest.eDest == SRT_Discard );
/* If ORDER BY makes no difference in the output then neither does
** DISTINCT so it can be removed too. */
sqlite3ExprListDelete( db, ref p.pOrderBy );
p.pOrderBy = null;
p.selFlags = (u16)( p.selFlags & ~SF_Distinct );
}
sqlite3SelectPrep( pParse, p, null );
pOrderBy = p.pOrderBy;
pTabList = p.pSrc;
pEList = p.pEList;
if ( pParse.nErr != 0 /*|| db.mallocFailed != 0 */ )
{
goto select_end;
}
isAgg = ( p.selFlags & SF_Aggregate ) != 0;
Debug.Assert( pEList != null );
/* Begin generating code.
*/
v = sqlite3GetVdbe( pParse );
if ( v == null )
goto select_end;
/* If writing to memory or generating a set
** only a single column may be output.
*/
#if !SQLITE_OMIT_SUBQUERY
if ( checkForMultiColumnSelectError( pParse, pDest, pEList.nExpr ) )
{
goto select_end;
}
#endif
/* Generate code for all sub-queries in the FROM clause
*/
#if !SQLITE_OMIT_SUBQUERY || !SQLITE_OMIT_VIEW
for ( i = 0; p.pPrior == null && i < pTabList.nSrc; i++ )
{
SrcList_item pItem = pTabList.a[i];
SelectDest dest = new SelectDest();
Select pSub = pItem.pSelect;
bool isAggSub;
if ( pSub == null || pItem.isPopulated != 0 )
continue;
/* Increment Parse.nHeight by the height of the largest expression
** tree refered to by this, the parent select. The child select
** may contain expression trees of at most
** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
** more conservative than necessary, but much easier than enforcing
** an exact limit.
*/
pParse.nHeight += sqlite3SelectExprHeight( p );
/* Check to see if the subquery can be absorbed into the parent. */
isAggSub = ( pSub.selFlags & SF_Aggregate ) != 0;
if ( flattenSubquery( pParse, p, i, isAgg, isAggSub ) != 0 )
{
if ( isAggSub )
{
isAgg = true;
p.selFlags |= SF_Aggregate;
}
i = -1;
}
else
{
sqlite3SelectDestInit( dest, SRT_EphemTab, pItem.iCursor );
Debug.Assert( 0 == pItem.isPopulated );
explainSetInteger( ref pItem.iSelectId, (int)pParse.iNextSelectId );
sqlite3Select( pParse, pSub, ref dest );
pItem.isPopulated = 1;
pItem.pTab.nRowEst = (uint)pSub.nSelectRow;
}
//if ( /* pParse.nErr != 0 || */ db.mallocFailed != 0 )
//{
// goto select_end;
//}
pParse.nHeight -= sqlite3SelectExprHeight( p );
pTabList = p.pSrc;
if ( !( pDest.eDest <= SRT_Discard ) )// if( null==IgnorableOrderby(pDest) )
{
pOrderBy = p.pOrderBy;
}
}
pEList = p.pEList;
#endif
pWhere = p.pWhere;
pGroupBy = p.pGroupBy;
pHaving = p.pHaving;
isDistinct = ( p.selFlags & SF_Distinct ) != 0;
#if !SQLITE_OMIT_COMPOUND_SELECT
/* If there is are a sequence of queries, do the earlier ones first.
*/
if ( p.pPrior != null )
{
if ( p.pRightmost == null )
{
Select pLoop, pRight = null;
int cnt = 0;
int mxSelect;
for ( pLoop = p; pLoop != null; pLoop = pLoop.pPrior, cnt++ )
{
pLoop.pRightmost = p;
pLoop.pNext = pRight;
pRight = pLoop;
}
mxSelect = db.aLimit[SQLITE_LIMIT_COMPOUND_SELECT];
if ( mxSelect != 0 && cnt > mxSelect )
{
sqlite3ErrorMsg( pParse, "too many terms in compound SELECT" );
goto select_end;
}
}
rc = multiSelect( pParse, p, pDest );
explainSetInteger( ref pParse.iSelectId, iRestoreSelectId );
return rc;
}
#endif
/* If possible, rewrite the query to use GROUP BY instead of DISTINCT.
** GROUP BY might use an index, DISTINCT never does.
*/
Debug.Assert( p.pGroupBy == null || ( p.selFlags & SF_Aggregate ) != 0 );
if ( ( p.selFlags & ( SF_Distinct | SF_Aggregate ) ) == SF_Distinct )
{
p.pGroupBy = sqlite3ExprListDup( db, p.pEList, 0 );
pGroupBy = p.pGroupBy;
p.selFlags = (u16)( p.selFlags & ~SF_Distinct );
}
/* If there is both a GROUP BY and an ORDER BY clause and they are
** identical, then disable the ORDER BY clause since the GROUP BY
** will cause elements to come out in the correct order. This is
** an optimization - the correct answer should result regardless.
** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER
** to disable this optimization for testing purposes.
*/
if ( sqlite3ExprListCompare( p.pGroupBy, pOrderBy ) == 0
&& ( db.flags & SQLITE_GroupByOrder ) == 0 )
{
pOrderBy = null;
}
/* If there is an ORDER BY clause, then this sorting
** index might end up being unused if the data can be
** extracted in pre-sorted order. If that is the case, then the
** OP_OpenEphemeral instruction will be changed to an OP_Noop once
** we figure out that the sorting index is not needed. The addrSortIndex
** variable is used to facilitate that change.
*/
if ( pOrderBy != null )
{
KeyInfo pKeyInfo;
pKeyInfo = keyInfoFromExprList( pParse, pOrderBy );
pOrderBy.iECursor = pParse.nTab++;
p.addrOpenEphm[2] = addrSortIndex =
sqlite3VdbeAddOp4( v, OP_OpenEphemeral,
pOrderBy.iECursor, pOrderBy.nExpr + 2, 0,
pKeyInfo, P4_KEYINFO_HANDOFF );
}
else
{
addrSortIndex = -1;
}
/* If the output is destined for a temporary table, open that table.
*/
if ( pDest.eDest == SRT_EphemTab )
{
sqlite3VdbeAddOp2( v, OP_OpenEphemeral, pDest.iParm, pEList.nExpr );
}
/* Set the limiter.
*/
iEnd = sqlite3VdbeMakeLabel( v );
p.nSelectRow = (double)LARGEST_INT64;
computeLimitRegisters( pParse, p, iEnd );
/* Open a virtual index to use for the distinct set.
*/
if ( ( p.selFlags & SF_Distinct ) != 0 )
{
KeyInfo pKeyInfo;
Debug.Assert( isAgg || pGroupBy != null );
distinct = pParse.nTab++;
pKeyInfo = keyInfoFromExprList( pParse, p.pEList );
sqlite3VdbeAddOp4( v, OP_OpenEphemeral, distinct, 0, 0,
pKeyInfo, P4_KEYINFO_HANDOFF );
sqlite3VdbeChangeP5( v, BTREE_UNORDERED );
}
else
{
distinct = -1;
}
/* Aggregate and non-aggregate queries are handled differently */
if ( !isAgg && pGroupBy == null )
{
/* This case is for non-aggregate queries
** Begin the database scan
*/
pWInfo = sqlite3WhereBegin( pParse, pTabList, pWhere, ref pOrderBy, 0 );
if ( pWInfo == null )
goto select_end;
if ( pWInfo.nRowOut < p.nSelectRow )
p.nSelectRow = pWInfo.nRowOut;
/* If sorting index that was created by a prior OP_OpenEphemeral
** instruction ended up not being needed, then change the OP_OpenEphemeral
** into an OP_Noop.
*/
if ( addrSortIndex >= 0 && pOrderBy == null )
{
sqlite3VdbeChangeToNoop( v, addrSortIndex, 1 );
p.addrOpenEphm[2] = -1;
}
/* Use the standard inner loop
*/
Debug.Assert( !isDistinct );
selectInnerLoop( pParse, p, pEList, 0, 0, pOrderBy, -1, pDest,
pWInfo.iContinue, pWInfo.iBreak );
/* End the database scan loop.
*/
sqlite3WhereEnd( pWInfo );
}
else
{
/* This is the processing for aggregate queries */
NameContext sNC; /* Name context for processing aggregate information */
int iAMem; /* First Mem address for storing current GROUP BY */
int iBMem; /* First Mem address for previous GROUP BY */
int iUseFlag; /* Mem address holding flag indicating that at least
** one row of the input to the aggregator has been
** processed */
int iAbortFlag; /* Mem address which causes query abort if positive */
int groupBySort; /* Rows come from source in GR BY' clause thanROUP BY order */
int addrEnd; /* End of processing for this SELECT */
/* Remove any and all aliases between the result set and the
** GROUP BY clause.
*/
if ( pGroupBy != null )
{
int k; /* Loop counter */
ExprList_item pItem; /* For looping over expression in a list */
for ( k = p.pEList.nExpr; k > 0; k-- )//, pItem++)
{
pItem = p.pEList.a[p.pEList.nExpr - k];
pItem.iAlias = 0;
}
for ( k = pGroupBy.nExpr; k > 0; k-- )//, pItem++ )
{
pItem = pGroupBy.a[pGroupBy.nExpr - k];
pItem.iAlias = 0;
}
if ( p.nSelectRow > (double)100 )
p.nSelectRow = (double)100;
}
else
{
p.nSelectRow = (double)1;
}
/* Create a label to jump to when we want to abort the query */
addrEnd = sqlite3VdbeMakeLabel( v );
/* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
** SELECT statement.
*/
sNC = new NameContext(); // memset(sNC, 0, sNC).Length;
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
sNC.pAggInfo = sAggInfo;
sAggInfo.nSortingColumn = pGroupBy != null ? pGroupBy.nExpr + 1 : 0;
sAggInfo.pGroupBy = pGroupBy;
sqlite3ExprAnalyzeAggList( sNC, pEList );
sqlite3ExprAnalyzeAggList( sNC, pOrderBy );
if ( pHaving != null )
{
sqlite3ExprAnalyzeAggregates( sNC, ref pHaving );
}
sAggInfo.nAccumulator = sAggInfo.nColumn;
for ( i = 0; i < sAggInfo.nFunc; i++ )
{
Debug.Assert( !ExprHasProperty( sAggInfo.aFunc[i].pExpr, EP_xIsSelect ) );
sqlite3ExprAnalyzeAggList( sNC, sAggInfo.aFunc[i].pExpr.x.pList );
}
// if ( db.mallocFailed != 0 ) goto select_end;
/* Processing for aggregates with GROUP BY is very different and
** much more complex than aggregates without a GROUP BY.
*/
if ( pGroupBy != null )
{
KeyInfo pKeyInfo; /* Keying information for the group by clause */
int j1; /* A-vs-B comparision jump */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int regOutputRow; /* Return address register for output subroutine */
int addrSetAbort; /* Set the abort flag and return */
int addrTopOfLoop; /* Top of the input loop */
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
/* If there is a GROUP BY clause we might need a sorting index to
** implement it. Allocate that sorting index now. If it turns out
** that we do not need it after all, the OpenEphemeral instruction
** will be converted into a Noop.
*/
sAggInfo.sortingIdx = pParse.nTab++;
pKeyInfo = keyInfoFromExprList( pParse, pGroupBy );
addrSortingIdx = sqlite3VdbeAddOp4( v, OP_OpenEphemeral,
sAggInfo.sortingIdx, sAggInfo.nSortingColumn,
0, pKeyInfo, P4_KEYINFO_HANDOFF );
/* Initialize memory locations used by GROUP BY aggregate processing
*/
iUseFlag = ++pParse.nMem;
iAbortFlag = ++pParse.nMem;
regOutputRow = ++pParse.nMem;
addrOutputRow = sqlite3VdbeMakeLabel( v );
regReset = ++pParse.nMem;
addrReset = sqlite3VdbeMakeLabel( v );
iAMem = pParse.nMem + 1;
pParse.nMem += pGroupBy.nExpr;
iBMem = pParse.nMem + 1;
pParse.nMem += pGroupBy.nExpr;
sqlite3VdbeAddOp2( v, OP_Integer, 0, iAbortFlag );
#if SQLITE_DEBUG
VdbeComment( v, "clear abort flag" );
#endif
sqlite3VdbeAddOp2( v, OP_Integer, 0, iUseFlag );
#if SQLITE_DEBUG
VdbeComment( v, "indicate accumulator empty" );
#endif
/* Begin a loop that will extract all source rows in GROUP BY order.
** This might involve two separate loops with an OP_Sort in between, or
** it might be a single loop that uses an index to extract information
** in the right order to begin with.
*/
sqlite3VdbeAddOp2( v, OP_Gosub, regReset, addrReset );
pWInfo = sqlite3WhereBegin( pParse, pTabList, pWhere, ref pGroupBy, 0 );
if ( pWInfo == null )
goto select_end;
if ( pGroupBy == null )
{
/* The optimizer is able to deliver rows in group by order so
** we do not have to sort. The OP_OpenEphemeral table will be
** cancelled later because we still need to use the pKeyInfo
*/
pGroupBy = p.pGroupBy;
groupBySort = 0;
}
else
{
/* Rows are coming out in undetermined order. We have to push
** each row into a sorting index, terminate the first loop,
** then loop over the sorting index in order to get the output
** in sorted order
*/
int regBase;
int regRecord;
int nCol;
int nGroupBy;
explainTempTable( pParse,
isDistinct && 0 == ( p.selFlags & SF_Distinct ) ? "DISTINCT" : "GROUP BY" );
groupBySort = 1;
nGroupBy = pGroupBy.nExpr;
nCol = nGroupBy + 1;
j = nGroupBy + 1;
for ( i = 0; i < sAggInfo.nColumn; i++ )
{
if ( sAggInfo.aCol[i].iSorterColumn >= j )
{
nCol++;
j++;
}
}
regBase = sqlite3GetTempRange( pParse, nCol );
sqlite3ExprCacheClear( pParse );
sqlite3ExprCodeExprList( pParse, pGroupBy, regBase, false );
sqlite3VdbeAddOp2( v, OP_Sequence, sAggInfo.sortingIdx, regBase + nGroupBy );
j = nGroupBy + 1;
for ( i = 0; i < sAggInfo.nColumn; i++ )
{
AggInfo_col pCol = sAggInfo.aCol[i];
if ( pCol.iSorterColumn >= j )
{
int r1 = j + regBase;
int r2;
r2 = sqlite3ExprCodeGetColumn( pParse,
pCol.pTab, pCol.iColumn, pCol.iTable, r1 );
if ( r1 != r2 )
{
sqlite3VdbeAddOp2( v, OP_SCopy, r2, r1 );
}
j++;
}
}
regRecord = sqlite3GetTempReg( pParse );
sqlite3VdbeAddOp3( v, OP_MakeRecord, regBase, nCol, regRecord );
sqlite3VdbeAddOp2( v, OP_IdxInsert, sAggInfo.sortingIdx, regRecord );
sqlite3ReleaseTempReg( pParse, regRecord );
sqlite3ReleaseTempRange( pParse, regBase, nCol );
sqlite3WhereEnd( pWInfo );
sqlite3VdbeAddOp2( v, OP_Sort, sAggInfo.sortingIdx, addrEnd );
#if SQLITE_DEBUG
VdbeComment( v, "GROUP BY sort" );
#endif
sAggInfo.useSortingIdx = 1;
sqlite3ExprCacheClear( pParse );
}
/* Evaluate the current GROUP BY terms and store in b0, b1, b2...
** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
** Then compare the current GROUP BY terms against the GROUP BY terms
** from the previous row currently stored in a0, a1, a2...
*/
addrTopOfLoop = sqlite3VdbeCurrentAddr( v );
sqlite3ExprCacheClear( pParse );
for ( j = 0; j < pGroupBy.nExpr; j++ )
{
if ( groupBySort != 0 )
{
sqlite3VdbeAddOp3( v, OP_Column, sAggInfo.sortingIdx, j, iBMem + j );
}
else
{
sAggInfo.directMode = 1;
sqlite3ExprCode( pParse, pGroupBy.a[j].pExpr, iBMem + j );
}
}
sqlite3VdbeAddOp4( v, OP_Compare, iAMem, iBMem, pGroupBy.nExpr,
pKeyInfo, P4_KEYINFO );
j1 = sqlite3VdbeCurrentAddr( v );
sqlite3VdbeAddOp3( v, OP_Jump, j1 + 1, 0, j1 + 1 );
/* Generate code that runs whenever the GROUP BY changes.
** Changes in the GROUP BY are detected by the previous code
** block. If there were no changes, this block is skipped.
**
** This code copies current group by terms in b0,b1,b2,...
** over to a0,a1,a2. It then calls the output subroutine
** and resets the aggregate accumulator registers in preparation
** for the next GROUP BY batch.
*/
sqlite3ExprCodeMove( pParse, iBMem, iAMem, pGroupBy.nExpr );
sqlite3VdbeAddOp2( v, OP_Gosub, regOutputRow, addrOutputRow );
#if SQLITE_DEBUG
VdbeComment( v, "output one row" );
#endif
sqlite3VdbeAddOp2( v, OP_IfPos, iAbortFlag, addrEnd );
#if SQLITE_DEBUG
VdbeComment( v, "check abort flag" );
#endif
sqlite3VdbeAddOp2( v, OP_Gosub, regReset, addrReset );
#if SQLITE_DEBUG
VdbeComment( v, "reset accumulator" );
#endif
/* Update the aggregate accumulators based on the content of
** the current row
*/
sqlite3VdbeJumpHere( v, j1 );
updateAccumulator( pParse, sAggInfo );
sqlite3VdbeAddOp2( v, OP_Integer, 1, iUseFlag );
#if SQLITE_DEBUG
VdbeComment( v, "indicate data in accumulator" );
#endif
/* End of the loop
*/
if ( groupBySort != 0 )
{
sqlite3VdbeAddOp2( v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop );
}
else
{
sqlite3WhereEnd( pWInfo );
sqlite3VdbeChangeToNoop( v, addrSortingIdx, 1 );
}
/* Output the final row of result
*/
sqlite3VdbeAddOp2( v, OP_Gosub, regOutputRow, addrOutputRow );
#if SQLITE_DEBUG
VdbeComment( v, "output final row" );
#endif
/* Jump over the subroutines
*/
sqlite3VdbeAddOp2( v, OP_Goto, 0, addrEnd );
/* Generate a subroutine that outputs a single row of the result
** set. This subroutine first looks at the iUseFlag. If iUseFlag
** is less than or equal to zero, the subroutine is a no-op. If
** the processing calls for the query to abort, this subroutine
** increments the iAbortFlag memory location before returning in
** order to signal the caller to abort.
*/
addrSetAbort = sqlite3VdbeCurrentAddr( v );
sqlite3VdbeAddOp2( v, OP_Integer, 1, iAbortFlag );
VdbeComment( v, "set abort flag" );
sqlite3VdbeAddOp1( v, OP_Return, regOutputRow );
sqlite3VdbeResolveLabel( v, addrOutputRow );
addrOutputRow = sqlite3VdbeCurrentAddr( v );
sqlite3VdbeAddOp2( v, OP_IfPos, iUseFlag, addrOutputRow + 2 );
VdbeComment( v, "Groupby result generator entry point" );
sqlite3VdbeAddOp1( v, OP_Return, regOutputRow );
finalizeAggFunctions( pParse, sAggInfo );
sqlite3ExprIfFalse( pParse, pHaving, addrOutputRow + 1, SQLITE_JUMPIFNULL );
selectInnerLoop( pParse, p, p.pEList, 0, 0, pOrderBy,
distinct, pDest,
addrOutputRow + 1, addrSetAbort );
sqlite3VdbeAddOp1( v, OP_Return, regOutputRow );
VdbeComment( v, "end groupby result generator" );
/* Generate a subroutine that will reset the group-by accumulator
*/
sqlite3VdbeResolveLabel( v, addrReset );
resetAccumulator( pParse, sAggInfo );
sqlite3VdbeAddOp1( v, OP_Return, regReset );
} /* endif pGroupBy. Begin aggregate queries without GROUP BY: */
else
{
ExprList pDel = null;
#if !SQLITE_OMIT_BTREECOUNT
Table pTab;
if ( ( pTab = isSimpleCount( p, sAggInfo ) ) != null )
{
/* If isSimpleCount() returns a pointer to a Table structure, then
** the SQL statement is of the form:
**
** SELECT count() FROM <tbl>
**
** where the Table structure returned represents table <tbl>.
**
** This statement is so common that it is optimized specially. The
** OP_Count instruction is executed either on the intkey table that
** contains the data for table <tbl> or on one of its indexes. It
** is better to execute the op on an index, as indexes are almost
** always spread across less pages than their corresponding tables.
*/
int iDb = sqlite3SchemaToIndex( pParse.db, pTab.pSchema );
int iCsr = pParse.nTab++; /* Cursor to scan b-tree */
Index pIdx; /* Iterator variable */
KeyInfo pKeyInfo = null; /* Keyinfo for scanned index */
Index pBest = null; /* Best index found so far */
int iRoot = pTab.tnum; /* Root page of scanned b-tree */
sqlite3CodeVerifySchema( pParse, iDb );
sqlite3TableLock( pParse, iDb, pTab.tnum, 0, pTab.zName );
/* Search for the index that has the least amount of columns. If
** there is such an index, and it has less columns than the table
** does, then we can assume that it consumes less space on disk and
** will therefore be cheaper to scan to determine the query result.
** In this case set iRoot to the root page number of the index b-tree
** and pKeyInfo to the KeyInfo structure required to navigate the
** index.
**
** (2011-04-15) Do not do a full scan of an unordered index.
**
** In practice the KeyInfo structure will not be used. It is only
** passed to keep OP_OpenRead happy.
*/
for ( pIdx = pTab.pIndex; pIdx != null; pIdx = pIdx.pNext )
{
if ( pIdx.bUnordered == 0 && ( null == pBest || pIdx.nColumn < pBest.nColumn ) )
{
pBest = pIdx;
}
}
if ( pBest != null && pBest.nColumn < pTab.nCol )
{
iRoot = pBest.tnum;
pKeyInfo = sqlite3IndexKeyinfo( pParse, pBest );
}
/* Open a read-only cursor, execute the OP_Count, close the cursor. */
sqlite3VdbeAddOp3( v, OP_OpenRead, iCsr, iRoot, iDb );
if ( pKeyInfo != null )
{
sqlite3VdbeChangeP4( v, -1, pKeyInfo, P4_KEYINFO_HANDOFF );
}
sqlite3VdbeAddOp2( v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem );
sqlite3VdbeAddOp1( v, OP_Close, iCsr );
explainSimpleCount( pParse, pTab, pBest );
}
else
#endif //* SQLITE_OMIT_BTREECOUNT */
{
/* Check if the query is of one of the following forms:
**
** SELECT min(x) FROM ...
** SELECT max(x) FROM ...
**
** If it is, then ask the code in where.c to attempt to sort results
** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause.
** If where.c is able to produce results sorted in this order, then
** add vdbe code to break out of the processing loop after the
** first iteration (since the first iteration of the loop is
** guaranteed to operate on the row with the minimum or maximum
** value of x, the only row required).
**
** A special flag must be passed to sqlite3WhereBegin() to slightly
** modify behavior as follows:
**
** + If the query is a "SELECT min(x)", then the loop coded by
** where.c should not iterate over any values with a NULL value
** for x.
**
** + The optimizer code in where.c (the thing that decides which
** index or indices to use) should place a different priority on
** satisfying the 'ORDER BY' clause than it does in other cases.
** Refer to code and comments in where.c for details.
*/
ExprList pMinMax = null;
int flag = minMaxQuery( p );
if ( flag != 0 )
{
Debug.Assert( !ExprHasProperty( p.pEList.a[0].pExpr, EP_xIsSelect ) );
pMinMax = sqlite3ExprListDup( db, p.pEList.a[0].pExpr.x.pList, 0 );
pDel = pMinMax;
if ( pMinMax != null )///* && 0 == db.mallocFailed */ )
{
pMinMax.a[0].sortOrder = (u8)( flag != WHERE_ORDERBY_MIN ? 1 : 0 );
pMinMax.a[0].pExpr.op = TK_COLUMN;
}
}
/* This case runs if the aggregate has no GROUP BY clause. The
** processing is much simpler since there is only a single row
** of output.
*/
resetAccumulator( pParse, sAggInfo );
pWInfo = sqlite3WhereBegin( pParse, pTabList, pWhere, ref pMinMax, (byte)flag );
if ( pWInfo == null )
{
sqlite3ExprListDelete( db, ref pDel );
goto select_end;
}
updateAccumulator( pParse, sAggInfo );
if ( pMinMax == null && flag != 0 )
{
sqlite3VdbeAddOp2( v, OP_Goto, 0, pWInfo.iBreak );
#if SQLITE_DEBUG
VdbeComment( v, "%s() by index",
( flag == WHERE_ORDERBY_MIN ? "min" : "max" ) );
#endif
}
sqlite3WhereEnd( pWInfo );
finalizeAggFunctions( pParse, sAggInfo );
}
pOrderBy = null;
sqlite3ExprIfFalse( pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL );
selectInnerLoop( pParse, p, p.pEList, 0, 0, null, -1,
pDest, addrEnd, addrEnd );
sqlite3ExprListDelete( db, ref pDel );
}
sqlite3VdbeResolveLabel( v, addrEnd );
} /* endif aggregate query */
if ( distinct >= 0 )
{
explainTempTable( pParse, "DISTINCT" );
}
/* If there is an ORDER BY clause, then we need to sort the results
** and send them to the callback one by one.
*/
if ( pOrderBy != null )
{
explainTempTable( pParse, "ORDER BY" );
generateSortTail( pParse, p, v, pEList.nExpr, pDest );
}
/* Jump here to skip this query
*/
sqlite3VdbeResolveLabel( v, iEnd );
/* The SELECT was successfully coded. Set the return code to 0
** to indicate no errors.
*/
rc = 0;
/* Control jumps to here if an error is encountered above, or upon
** successful coding of the SELECT.
*/
select_end:
explainSetInteger( ref pParse.iSelectId, iRestoreSelectId );
/* Identify column names if results of the SELECT are to be output.
*/
if ( rc == SQLITE_OK && pDest.eDest == SRT_Output )
{
generateColumnNames( pParse, pTabList, pEList );
}
sqlite3DbFree( db, ref sAggInfo.aCol );
sqlite3DbFree( db, ref sAggInfo.aFunc );
return rc;
}
#if SQLITE_DEBUG
/*
*******************************************************************************
** The following code is used for testing and debugging only. The code
** that follows does not appear in normal builds.
**
** These routines are used to print out the content of all or part of a
** parse structures such as Select or Expr. Such printouts are useful
** for helping to understand what is happening inside the code generator
** during the execution of complex SELECT statements.
**
** These routine are not called anywhere from within the normal
** code base. Then are intended to be called from within the debugger
** or from temporary "printf" statements inserted for debugging.
*/
void sqlite3PrintExpr( Expr p )
{
if ( !ExprHasProperty( p, EP_IntValue ) && p.u.zToken != null )
{
sqlite3DebugPrintf( "(%s", p.u.zToken );
}
else
{
sqlite3DebugPrintf( "(%d", p.op );
}
if ( p.pLeft != null )
{
sqlite3DebugPrintf( " " );
sqlite3PrintExpr( p.pLeft );
}
if ( p.pRight != null )
{
sqlite3DebugPrintf( " " );
sqlite3PrintExpr( p.pRight );
}
sqlite3DebugPrintf( ")" );
}
void sqlite3PrintExprList( ExprList pList )
{
int i;
for ( i = 0; i < pList.nExpr; i++ )
{
sqlite3PrintExpr( pList.a[i].pExpr );
if ( i < pList.nExpr - 1 )
{
sqlite3DebugPrintf( ", " );
}
}
}
void sqlite3PrintSelect( Select p, int indent )
{
sqlite3DebugPrintf( "%*sSELECT(%p) ", indent, string.Empty, p );
sqlite3PrintExprList( p.pEList );
sqlite3DebugPrintf( "\n" );
if ( p.pSrc != null )
{
string zPrefix;
int i;
zPrefix = "FROM";
for ( i = 0; i < p.pSrc.nSrc; i++ )
{
SrcList_item pItem = p.pSrc.a[i];
sqlite3DebugPrintf( "%*s ", indent + 6, zPrefix );
zPrefix = string.Empty;
if ( pItem.pSelect != null )
{
sqlite3DebugPrintf( "(\n" );
sqlite3PrintSelect( pItem.pSelect, indent + 10 );
sqlite3DebugPrintf( "%*s)", indent + 8, string.Empty );
}
else if ( pItem.zName != null )
{
sqlite3DebugPrintf( "%s", pItem.zName );
}
if ( pItem.pTab != null )
{
sqlite3DebugPrintf( "(vtable: %s)", pItem.pTab.zName );
}
if ( pItem.zAlias != null )
{
sqlite3DebugPrintf( " AS %s", pItem.zAlias );
}
if ( i < p.pSrc.nSrc - 1 )
{
sqlite3DebugPrintf( "," );
}
sqlite3DebugPrintf( "\n" );
}
}
if ( p.pWhere != null )
{
sqlite3DebugPrintf( "%*s WHERE ", indent, string.Empty );
sqlite3PrintExpr( p.pWhere );
sqlite3DebugPrintf( "\n" );
}
if ( p.pGroupBy != null )
{
sqlite3DebugPrintf( "%*s GROUP BY ", indent, string.Empty );
sqlite3PrintExprList( p.pGroupBy );
sqlite3DebugPrintf( "\n" );
}
if ( p.pHaving != null )
{
sqlite3DebugPrintf( "%*s HAVING ", indent, string.Empty );
sqlite3PrintExpr( p.pHaving );
sqlite3DebugPrintf( "\n" );
}
if ( p.pOrderBy != null )
{
sqlite3DebugPrintf( "%*s ORDER BY ", indent, string.Empty );
sqlite3PrintExprList( p.pOrderBy );
sqlite3DebugPrintf( "\n" );
}
}
/* End of the structure debug printing code
*****************************************************************************/
#endif // * defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */
}
}