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chromium / external / github.com / pwnall / sqlite / refs/heads/branch-3.3.6 / . / src / select.c
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/*
** 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.
**
** $Id: select.c,v 1.313 2006/04/26 17:39:34 drh Exp $
*/
#include "sqliteInt.h"
/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
*/
static void clearSelect(Select *p){
sqlite3ExprListDelete(p->pEList);
sqlite3SrcListDelete(p->pSrc);
sqlite3ExprDelete(p->pWhere);
sqlite3ExprListDelete(p->pGroupBy);
sqlite3ExprDelete(p->pHaving);
sqlite3ExprListDelete(p->pOrderBy);
sqlite3SelectDelete(p->pPrior);
sqlite3ExprDelete(p->pLimit);
sqlite3ExprDelete(p->pOffset);
}
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
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;
pNew = sqliteMalloc( sizeof(*pNew) );
assert( !pOffset || pLimit ); /* Can't have OFFSET without LIMIT. */
if( pNew==0 ){
pNew = &standin;
memset(pNew, 0, sizeof(*pNew));
}
if( pEList==0 ){
pEList = sqlite3ExprListAppend(0, sqlite3Expr(TK_ALL,0,0,0), 0);
}
pNew->pEList = pEList;
pNew->pSrc = pSrc;
pNew->pWhere = pWhere;
pNew->pGroupBy = pGroupBy;
pNew->pHaving = pHaving;
pNew->pOrderBy = pOrderBy;
pNew->isDistinct = isDistinct;
pNew->op = TK_SELECT;
pNew->pLimit = pLimit;
pNew->pOffset = pOffset;
pNew->iLimit = -1;
pNew->iOffset = -1;
pNew->addrOpenVirt[0] = -1;
pNew->addrOpenVirt[1] = -1;
pNew->addrOpenVirt[2] = -1;
if( pNew==&standin) {
clearSelect(pNew);
pNew = 0;
}
return pNew;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(Select *p){
if( p ){
clearSelect(p);
sqliteFree(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.
*/
int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
int jointype = 0;
Token *apAll[3];
Token *p;
static const struct {
const char zKeyword[8];
u8 nChar;
u8 code;
} keywords[] = {
{ "natural", 7, JT_NATURAL },
{ "left", 4, JT_LEFT|JT_OUTER },
{ "right", 5, JT_RIGHT|JT_OUTER },
{ "full", 4, JT_LEFT|JT_RIGHT|JT_OUTER },
{ "outer", 5, JT_OUTER },
{ "inner", 5, JT_INNER },
{ "cross", 5, JT_INNER|JT_CROSS },
};
int i, j;
apAll[0] = pA;
apAll[1] = pB;
apAll[2] = pC;
for(i=0; i<3 && apAll[i]; i++){
p = apAll[i];
for(j=0; j<sizeof(keywords)/sizeof(keywords[0]); j++){
if( p->n==keywords[j].nChar
&& sqlite3StrNICmp((char*)p->z, keywords[j].zKeyword, p->n)==0 ){
jointype |= keywords[j].code;
break;
}
}
if( j>=sizeof(keywords)/sizeof(keywords[0]) ){
jointype |= JT_ERROR;
break;
}
}
if(
(jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
(jointype & JT_ERROR)!=0
){
const char *zSp1 = " ";
const char *zSp2 = " ";
if( pB==0 ){ zSp1++; }
if( pC==0 ){ zSp2++; }
sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
"%T%s%T%s%T", pA, zSp1, pB, zSp2, pC);
jointype = JT_INNER;
}else if( jointype & JT_RIGHT ){
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, const char *zCol){
int i;
for(i=0; i<pTab->nCol; i++){
if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
}
return -1;
}
/*
** Set the value of a token to a '\000'-terminated string.
*/
static void setToken(Token *p, const char *z){
p->z = (u8*)z;
p->n = z ? strlen(z) : 0;
p->dyn = 0;
}
/*
** Create an expression node for an identifier with the name of zName
*/
static Expr *createIdExpr(const char *zName){
Token dummy;
setToken(&dummy, zName);
return sqlite3Expr(TK_ID, 0, 0, &dummy);
}
/*
** Add a term to the WHERE expression in *ppExpr that requires the
** zCol column to be equal in the two tables pTab1 and pTab2.
*/
static void addWhereTerm(
const char *zCol, /* Name of the column */
const Table *pTab1, /* First table */
const char *zAlias1, /* Alias for first table. May be NULL */
const Table *pTab2, /* Second table */
const char *zAlias2, /* Alias for second table. May be NULL */
int iRightJoinTable, /* VDBE cursor for the right table */
Expr **ppExpr /* Add the equality term to this expression */
){
Expr *pE1a, *pE1b, *pE1c;
Expr *pE2a, *pE2b, *pE2c;
Expr *pE;
pE1a = createIdExpr(zCol);
pE2a = createIdExpr(zCol);
if( zAlias1==0 ){
zAlias1 = pTab1->zName;
}
pE1b = createIdExpr(zAlias1);
if( zAlias2==0 ){
zAlias2 = pTab2->zName;
}
pE2b = createIdExpr(zAlias2);
pE1c = sqlite3Expr(TK_DOT, pE1b, pE1a, 0);
pE2c = sqlite3Expr(TK_DOT, pE2b, pE2a, 0);
pE = sqlite3Expr(TK_EQ, pE1c, pE2c, 0);
ExprSetProperty(pE, EP_FromJoin);
pE->iRightJoinTable = iRightJoinTable;
*ppExpr = sqlite3ExprAnd(*ppExpr, pE);
}
/*
** 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 ){
ExprSetProperty(p, EP_FromJoin);
p->iRightJoinTable = 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, j; /* Loop counters */
struct SrcList_item *pLeft; /* Left table being joined */
struct 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++, pRight++, pLeft++){
Table *pLeftTab = pLeft->pTab;
Table *pRightTab = pRight->pTab;
if( pLeftTab==0 || pRightTab==0 ) continue;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if( pLeft->jointype & JT_NATURAL ){
if( pLeft->pOn || pLeft->pUsing ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
}
for(j=0; j<pLeftTab->nCol; j++){
char *zName = pLeftTab->aCol[j].zName;
if( columnIndex(pRightTab, zName)>=0 ){
addWhereTerm(zName, pLeftTab, pLeft->zAlias,
pRightTab, pRight->zAlias,
pRight->iCursor, &p->pWhere);
}
}
}
/* Disallow both ON and USING clauses in the same join
*/
if( pLeft->pOn && pLeft->pUsing ){
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( pLeft->pOn ){
setJoinExpr(pLeft->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(p->pWhere, pLeft->pOn);
pLeft->pOn = 0;
}
/* 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( pLeft->pUsing ){
IdList *pList = pLeft->pUsing;
for(j=0; j<pList->nId; j++){
char *zName = pList->a[j].zName;
if( columnIndex(pLeftTab, zName)<0 || columnIndex(pRightTab, zName)<0 ){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
return 1;
}
addWhereTerm(zName, pLeftTab, pLeft->zAlias,
pRightTab, pRight->zAlias,
pRight->iCursor, &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 */
){
Vdbe *v = pParse->pVdbe;
sqlite3ExprCodeExprList(pParse, pOrderBy);
sqlite3VdbeAddOp(v, OP_Sequence, pOrderBy->iECursor, 0);
sqlite3VdbeAddOp(v, OP_Pull, pOrderBy->nExpr + 1, 0);
sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 2, 0);
sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iECursor, 0);
if( pSelect->iLimit>=0 ){
int addr1, addr2;
addr1 = sqlite3VdbeAddOp(v, OP_IfMemZero, pSelect->iLimit+1, 0);
sqlite3VdbeAddOp(v, OP_MemIncr, -1, pSelect->iLimit+1);
addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp(v, OP_Last, pOrderBy->iECursor, 0);
sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
sqlite3VdbeJumpHere(v, addr2);
pSelect->iLimit = -1;
}
}
/*
** 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 */
int nPop /* Number of times to pop stack when jumping */
){
if( p->iOffset>=0 && iContinue!=0 ){
int addr;
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iOffset);
addr = sqlite3VdbeAddOp(v, OP_IfMemNeg, p->iOffset, 0);
if( nPop>0 ){
sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
}
sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
VdbeComment((v, "# skip OFFSET records"));
sqlite3VdbeJumpHere(v, addr);
}
}
/*
** Add code that will check to make sure the top N elements of the
** stack are distinct. 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(
Vdbe *v, /* Generate code into this VM */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
int N /* The top N elements of the stack must be distinct */
){
sqlite3VdbeAddOp(v, OP_MakeRecord, -N, 0);
sqlite3VdbeAddOp(v, OP_Distinct, iTab, sqlite3VdbeCurrentAddr(v)+3);
sqlite3VdbeAddOp(v, OP_Pop, N+1, 0);
sqlite3VdbeAddOp(v, OP_Goto, 0, addrRepeat);
VdbeComment((v, "# skip indistinct records"));
sqlite3VdbeAddOp(v, OP_IdxInsert, iTab, 0);
}
/*
** 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 int 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 */
int eDest, /* How to dispose of the results */
int iParm, /* An argument to the disposal method */
int iContinue, /* Jump here to continue with next row */
int iBreak, /* Jump here to break out of the inner loop */
char *aff /* affinity string if eDest is SRT_Union */
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
if( v==0 ) return 0;
assert( pEList!=0 );
/* If there was a LIMIT clause on the SELECT statement, then do the check
** to see if this row should be output.
*/
hasDistinct = distinct>=0 && pEList->nExpr>0;
if( pOrderBy==0 && !hasDistinct ){
codeOffset(v, p, iContinue, 0);
}
/* Pull the requested columns.
*/
if( nColumn>0 ){
for(i=0; i<nColumn; i++){
sqlite3VdbeAddOp(v, OP_Column, srcTab, i);
}
}else{
nColumn = pEList->nExpr;
sqlite3ExprCodeExprList(pParse, pEList);
}
/* 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 ){
assert( pEList!=0 );
assert( pEList->nExpr==nColumn );
codeDistinct(v, distinct, iContinue, nColumn);
if( pOrderBy==0 ){
codeOffset(v, p, iContinue, nColumn);
}
}
switch( eDest ){
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
case SRT_Union: {
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
if( aff ){
sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
}
sqlite3VdbeAddOp(v, OP_IdxInsert, iParm, 0);
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: {
int addr;
addr = sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
sqlite3VdbeAddOp(v, OP_NotFound, iParm, addr+3);
sqlite3VdbeAddOp(v, OP_Delete, iParm, 0);
break;
}
#endif
/* Store the result as data using a unique key.
*/
case SRT_Table:
case SRT_VirtualTab: {
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p);
}else{
sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
}
break;
}
#ifndef 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 addr1 = sqlite3VdbeCurrentAddr(v);
int addr2;
assert( nColumn==1 );
sqlite3VdbeAddOp(v, OP_NotNull, -1, addr1+3);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
if( pOrderBy ){
/* 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);
}else{
char affinity = (iParm>>16)&0xFF;
affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, affinity);
sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1);
sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
}
sqlite3VdbeJumpHere(v, addr2);
break;
}
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp(v, OP_MemInt, 1, iParm);
sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
/* 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: {
assert( nColumn==1 );
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p);
}else{
sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
/* The LIMIT clause will jump out of the loop for us */
}
break;
}
#endif /* #ifndef 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_Subroutine:
case SRT_Callback: {
if( pOrderBy ){
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
pushOntoSorter(pParse, pOrderBy, p);
}else if( eDest==SRT_Subroutine ){
sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
}else{
sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
}
break;
}
#if !defined(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: {
assert( eDest==SRT_Discard );
sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit>=0 && pOrderBy==0 ){
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
}
return 0;
}
/*
** 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 P3 field of an opcode using
** P3_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;
struct ExprList_item *pItem;
int i;
nExpr = pList->nExpr;
pInfo = sqliteMalloc( sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
if( pInfo ){
pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
pInfo->nField = nExpr;
pInfo->enc = ENC(db);
for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
CollSeq *pColl;
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
if( !pColl ){
pColl = db->pDfltColl;
}
pInfo->aColl[i] = pColl;
pInfo->aSortOrder[i] = pItem->sortOrder;
}
}
return pInfo;
}
/*
** 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 */
int eDest, /* Write the sorted results here */
int iParm /* Optional parameter associated with eDest */
){
int brk = sqlite3VdbeMakeLabel(v);
int cont = sqlite3VdbeMakeLabel(v);
int addr;
int iTab;
int pseudoTab;
ExprList *pOrderBy = p->pOrderBy;
iTab = pOrderBy->iECursor;
if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
pseudoTab = pParse->nTab++;
sqlite3VdbeAddOp(v, OP_OpenPseudo, pseudoTab, 0);
sqlite3VdbeAddOp(v, OP_SetNumColumns, pseudoTab, nColumn);
}
addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk);
codeOffset(v, p, cont, 0);
if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
}
sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr + 1);
switch( eDest ){
case SRT_Table:
case SRT_VirtualTab: {
sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case SRT_Set: {
assert( nColumn==1 );
sqlite3VdbeAddOp(v, OP_NotNull, -1, sqlite3VdbeCurrentAddr(v)+3);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
sqlite3VdbeAddOp(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+3);
sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, "c", P3_STATIC);
sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
break;
}
case SRT_Mem: {
assert( nColumn==1 );
sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
case SRT_Callback:
case SRT_Subroutine: {
int i;
sqlite3VdbeAddOp(v, OP_Insert, pseudoTab, 0);
for(i=0; i<nColumn; i++){
sqlite3VdbeAddOp(v, OP_Column, pseudoTab, i);
}
if( eDest==SRT_Callback ){
sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
}else{
sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
}
break;
}
default: {
/* Do nothing */
break;
}
}
/* Jump to the end of the loop when the LIMIT is reached
*/
if( p->iLimit>=0 ){
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
}
/* The bottom of the loop
*/
sqlite3VdbeResolveLabel(v, cont);
sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
sqlite3VdbeResolveLabel(v, brk);
if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
sqlite3VdbeAddOp(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 const char *columnType(
NameContext *pNC,
Expr *pExpr,
const char **pzOriginDb,
const char **pzOriginTab,
const char **pzOriginCol
){
char const *zType = 0;
char const *zOriginDb = 0;
char const *zOriginTab = 0;
char const *zOriginCol = 0;
int j;
if( pExpr==0 || pNC->pSrcList==0 ) return 0;
/* The TK_AS operator can only occur in ORDER BY, GROUP BY, HAVING,
** and LIMIT clauses. But pExpr originates in the result set of a
** SELECT. So pExpr can never contain an AS operator.
*/
assert( pExpr->op!=TK_AS );
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 = 0; /* Table structure column is extracted from */
Select *pS = 0; /* Select the column is extracted from */
int iCol = pExpr->iColumn; /* Index of column in pTab */
while( pNC && !pTab ){
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==0 ){
/* FIX ME:
** This can occurs if you have something like "SELECT new.x;" inside
** a trigger. In other words, if you reference the special "new"
** table in the result set of a select. We do not have a good way
** to find the actual table type, so call it "TEXT". This is really
** something of a bug, but I do not know how to fix it.
**
** This code does not produce the correct answer - it just prevents
** a segfault. See ticket #1229.
*/
zType = "TEXT";
break;
}
assert( pTab );
#ifndef SQLITE_OMIT_SUBQUERY
if( pS ){
/* 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 && 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;
Expr *p = pS->pEList->a[iCol].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = 0;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
}
}else
#endif
if( pTab->pSchema ){
/* A real table */
assert( !pS );
if( iCol<0 ) iCol = pTab->iPKey;
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 ){
int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
zOriginDb = pNC->pParse->db->aDb[iDb].zName;
}
}
break;
}
#ifndef 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;
Select *pS = pExpr->pSelect;
Expr *p = pS->pEList->a[0].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
break;
}
#endif
}
if( pzOriginDb ){
assert( pzOriginTab && pzOriginCol );
*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 */
){
Vdbe *v = pParse->pVdbe;
int i;
NameContext sNC;
sNC.pSrcList = pTabList;
sNC.pParse = pParse;
for(i=0; i<pEList->nExpr; i++){
Expr *p = pEList->a[i].pExpr;
const char *zOrigDb = 0;
const char *zOrigTab = 0;
const char *zOrigCol = 0;
const char *zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
/* The vdbe must make it's 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_DECLTYPE, zType, P3_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, P3_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, P3_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, P3_TRANSIENT);
}
}
/*
** 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;
int fullNames, shortNames;
#ifndef SQLITE_OMIT_EXPLAIN
/* If this is an EXPLAIN, skip this step */
if( pParse->explain ){
return;
}
#endif
assert( v!=0 );
if( pParse->colNamesSet || v==0 || sqlite3MallocFailed() ) 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( p==0 ) continue;
if( pEList->a[i].zName ){
char *zName = pEList->a[i].zName;
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, strlen(zName));
continue;
}
if( p->op==TK_COLUMN && pTabList ){
Table *pTab;
char *zCol;
int iCol = p->iColumn;
for(j=0; j<pTabList->nSrc && pTabList->a[j].iCursor!=p->iTable; j++){}
assert( j<pTabList->nSrc );
pTab = pTabList->a[j].pTab;
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zCol = "rowid";
}else{
zCol = pTab->aCol[iCol].zName;
}
if( !shortNames && !fullNames && p->span.z && p->span.z[0] ){
sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
}else if( fullNames || (!shortNames && pTabList->nSrc>1) ){
char *zName = 0;
char *zTab;
zTab = pTabList->a[j].zAlias;
if( fullNames || zTab==0 ) zTab = pTab->zName;
sqlite3SetString(&zName, zTab, ".", zCol, (char*)0);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, P3_DYNAMIC);
}else{
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, strlen(zCol));
}
}else if( p->span.z && p->span.z[0] ){
sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
/* sqlite3VdbeCompressSpace(v, addr); */
}else{
char zName[30];
assert( p->op!=TK_COLUMN || pTabList==0 );
sprintf(zName, "column%d", i+1);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, 0);
}
}
generateColumnTypes(pParse, pTabList, pEList);
}
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Name of the connection operator, used for error messages.
*/
static const char *selectOpName(int id){
char *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 */
/*
** Forward declaration
*/
static int prepSelectStmt(Parse*, Select*);
/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqlite3ResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){
Table *pTab;
int i, j;
ExprList *pEList;
Column *aCol, *pCol;
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
if( prepSelectStmt(pParse, pSelect) ){
return 0;
}
if( sqlite3SelectResolve(pParse, pSelect, 0) ){
return 0;
}
pTab = sqliteMalloc( sizeof(Table) );
if( pTab==0 ){
return 0;
}
pTab->nRef = 1;
pTab->zName = zTabName ? sqliteStrDup(zTabName) : 0;
pEList = pSelect->pEList;
pTab->nCol = pEList->nExpr;
assert( pTab->nCol>0 );
pTab->aCol = aCol = sqliteMalloc( sizeof(pTab->aCol[0])*pTab->nCol );
for(i=0, pCol=aCol; i<pTab->nCol; i++, pCol++){
Expr *p, *pR;
char *zType;
char *zName;
char *zBasename;
CollSeq *pColl;
int cnt;
NameContext sNC;
/* Get an appropriate name for the column
*/
p = pEList->a[i].pExpr;
assert( p->pRight==0 || p->pRight->token.z==0 || p->pRight->token.z[0]!=0 );
if( (zName = pEList->a[i].zName)!=0 ){
/* If the column contains an "AS <name>" phrase, use <name> as the name */
zName = sqliteStrDup(zName);
}else if( p->op==TK_DOT
&& (pR=p->pRight)!=0 && pR->token.z && pR->token.z[0] ){
/* For columns of the from A.B use B as the name */
zName = sqlite3MPrintf("%T", &pR->token);
}else if( p->span.z && p->span.z[0] ){
/* Use the original text of the column expression as its name */
zName = sqlite3MPrintf("%T", &p->span);
}else{
/* If all else fails, make up a name */
zName = sqlite3MPrintf("column%d", i+1);
}
sqlite3Dequote(zName);
if( sqlite3MallocFailed() ){
sqliteFree(zName);
sqlite3DeleteTable(0, pTab);
return 0;
}
/* Make sure the column name is unique. If the name is not unique,
** append a integer to the name so that it becomes unique.
*/
zBasename = zName;
for(j=cnt=0; j<i; j++){
if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
zName = sqlite3MPrintf("%s:%d", zBasename, ++cnt);
j = -1;
if( zName==0 ) break;
}
}
if( zBasename!=zName ){
sqliteFree(zBasename);
}
pCol->zName = zName;
/* Get the typename, type affinity, and collating sequence for the
** column.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pSrcList = pSelect->pSrc;
zType = sqliteStrDup(columnType(&sNC, p, 0, 0, 0));
pCol->zType = zType;
pCol->affinity = sqlite3ExprAffinity(p);
pColl = sqlite3ExprCollSeq(pParse, p);
if( pColl ){
pCol->zColl = sqliteStrDup(pColl->zName);
}
}
pTab->iPKey = -1;
return pTab;
}
/*
** Prepare a SELECT statement for processing by doing the following
** things:
**
** (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[].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.
**
** Return 0 on success. If there are problems, leave an error message
** in pParse and return non-zero.
*/
static int prepSelectStmt(Parse *pParse, Select *p){
int i, j, k, rc;
SrcList *pTabList;
ExprList *pEList;
struct SrcList_item *pFrom;
if( p==0 || p->pSrc==0 || sqlite3MallocFailed() ){
return 1;
}
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, p->pSrc);
/* 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 structure to describe the subquery.
*/
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab;
if( pFrom->pTab!=0 ){
/* This statement has already been prepared. There is no need
** to go further. */
assert( i==0 );
return 0;
}
if( pFrom->zName==0 ){
#ifndef SQLITE_OMIT_SUBQUERY
/* A sub-query in the FROM clause of a SELECT */
assert( pFrom->pSelect!=0 );
if( pFrom->zAlias==0 ){
pFrom->zAlias =
sqlite3MPrintf("sqlite_subquery_%p_", (void*)pFrom->pSelect);
}
assert( pFrom->pTab==0 );
pFrom->pTab = pTab =
sqlite3ResultSetOfSelect(pParse, pFrom->zAlias, pFrom->pSelect);
if( pTab==0 ){
return 1;
}
/* The isTransient flag indicates that the Table structure has been
** dynamically allocated and may be freed at any time. In other words,
** pTab is not pointing to a persistent table structure that defines
** part of the schema. */
pTab->isTransient = 1;
#endif
}else{
/* An ordinary table or view name in the FROM clause */
assert( pFrom->pTab==0 );
pFrom->pTab = pTab =
sqlite3LocateTable(pParse,pFrom->zName,pFrom->zDatabase);
if( pTab==0 ){
return 1;
}
pTab->nRef++;
#ifndef SQLITE_OMIT_VIEW
if( pTab->pSelect ){
/* We reach here if the named table is a really a view */
if( sqlite3ViewGetColumnNames(pParse, pTab) ){
return 1;
}
/* If pFrom->pSelect!=0 it means we are dealing with a
** view within a view. The SELECT structure has already been
** copied by the outer view so we can skip the copy step here
** in the inner view.
*/
if( pFrom->pSelect==0 ){
pFrom->pSelect = sqlite3SelectDup(pTab->pSelect);
}
}
#endif
}
}
/* Process NATURAL keywords, and ON and USING clauses of joins.
*/
if( sqliteProcessJoin(pParse, p) ) return 1;
/* 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;
if( pE->op==TK_DOT && pE->pRight && pE->pRight->op==TK_ALL
&& pE->pLeft && pE->pLeft->op==TK_ID ) break;
}
rc = 0;
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.
*/
struct ExprList_item *a = pEList->a;
ExprList *pNew = 0;
int flags = pParse->db->flags;
int longNames = (flags & SQLITE_FullColNames)!=0 &&
(flags & SQLITE_ShortColNames)==0;
for(k=0; k<pEList->nExpr; k++){
Expr *pE = a[k].pExpr;
if( pE->op!=TK_ALL &&
(pE->op!=TK_DOT || pE->pRight==0 || pE->pRight->op!=TK_ALL) ){
/* This particular expression does not need to be expanded.
*/
pNew = sqlite3ExprListAppend(pNew, a[k].pExpr, 0);
if( pNew ){
pNew->a[pNew->nExpr-1].zName = a[k].zName;
}else{
rc = 1;
}
a[k].pExpr = 0;
a[k].zName = 0;
}else{
/* This expression is a "*" or a "TABLE.*" and needs to be
** expanded. */
int tableSeen = 0; /* Set to 1 when TABLE matches */
char *zTName; /* text of name of TABLE */
if( pE->op==TK_DOT && pE->pLeft ){
zTName = sqlite3NameFromToken(&pE->pLeft->token);
}else{
zTName = 0;
}
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab = pFrom->pTab;
char *zTabName = pFrom->zAlias;
if( zTabName==0 || zTabName[0]==0 ){
zTabName = pTab->zName;
}
if( zTName && (zTabName==0 || zTabName[0]==0 ||
sqlite3StrICmp(zTName, zTabName)!=0) ){
continue;
}
tableSeen = 1;
for(j=0; j<pTab->nCol; j++){
Expr *pExpr, *pRight;
char *zName = pTab->aCol[j].zName;
if( i>0 ){
struct SrcList_item *pLeft = &pTabList->a[i-1];
if( (pLeft->jointype & JT_NATURAL)!=0 &&
columnIndex(pLeft->pTab, zName)>=0 ){
/* In a NATURAL join, omit the join columns from the
** table on the right */
continue;
}
if( sqlite3IdListIndex(pLeft->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(TK_ID, 0, 0, 0);
if( pRight==0 ) break;
setToken(&pRight->token, zName);
if( zTabName && (longNames || pTabList->nSrc>1) ){
Expr *pLeft = sqlite3Expr(TK_ID, 0, 0, 0);
pExpr = sqlite3Expr(TK_DOT, pLeft, pRight, 0);
if( pExpr==0 ) break;
setToken(&pLeft->token, zTabName);
setToken(&pExpr->span, sqlite3MPrintf("%s.%s", zTabName, zName));
pExpr->span.dyn = 1;
pExpr->token.z = 0;
pExpr->token.n = 0;
pExpr->token.dyn = 0;
}else{
pExpr = pRight;
pExpr->span = pExpr->token;
}
if( longNames ){
pNew = sqlite3ExprListAppend(pNew, pExpr, &pExpr->span);
}else{
pNew = sqlite3ExprListAppend(pNew, pExpr, &pRight->token);
}
}
}
if( !tableSeen ){
if( zTName ){
sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
}else{
sqlite3ErrorMsg(pParse, "no tables specified");
}
rc = 1;
}
sqliteFree(zTName);
}
}
sqlite3ExprListDelete(pEList);
p->pEList = pNew;
}
return rc;
}
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** This routine associates entries in an ORDER BY expression list with
** columns in a result. For each ORDER BY expression, the opcode of
** the top-level node is changed to TK_COLUMN and the iColumn value of
** the top-level node is filled in with column number and the iTable
** value of the top-level node is filled with iTable parameter.
**
** If there are prior SELECT clauses, they are processed first. A match
** in an earlier SELECT takes precedence over a later SELECT.
**
** Any entry that does not match is flagged as an error. The number
** of errors is returned.
*/
static int matchOrderbyToColumn(
Parse *pParse, /* A place to leave error messages */
Select *pSelect, /* Match to result columns of this SELECT */
ExprList *pOrderBy, /* The ORDER BY values to match against columns */
int iTable, /* Insert this value in iTable */
int mustComplete /* If TRUE all ORDER BYs must match */
){
int nErr = 0;
int i, j;
ExprList *pEList;
if( pSelect==0 || pOrderBy==0 ) return 1;
if( mustComplete ){
for(i=0; i<pOrderBy->nExpr; i++){ pOrderBy->a[i].done = 0; }
}
if( prepSelectStmt(pParse, pSelect) ){
return 1;
}
if( pSelect->pPrior ){
if( matchOrderbyToColumn(pParse, pSelect->pPrior, pOrderBy, iTable, 0) ){
return 1;
}
}
pEList = pSelect->pEList;
for(i=0; i<pOrderBy->nExpr; i++){
Expr *pE = pOrderBy->a[i].pExpr;
int iCol = -1;
if( pOrderBy->a[i].done ) continue;
if( sqlite3ExprIsInteger(pE, &iCol) ){
if( iCol<=0 || iCol>pEList->nExpr ){
sqlite3ErrorMsg(pParse,
"ORDER BY position %d should be between 1 and %d",
iCol, pEList->nExpr);
nErr++;
break;
}
if( !mustComplete ) continue;
iCol--;
}
for(j=0; iCol<0 && j<pEList->nExpr; j++){
if( pEList->a[j].zName && (pE->op==TK_ID || pE->op==TK_STRING) ){
char *zName, *zLabel;
zName = pEList->a[j].zName;
zLabel = sqlite3NameFromToken(&pE->token);
assert( zLabel!=0 );
if( sqlite3StrICmp(zName, zLabel)==0 ){
iCol = j;
}
sqliteFree(zLabel);
}
if( iCol<0 && sqlite3ExprCompare(pE, pEList->a[j].pExpr) ){
iCol = j;
}
}
if( iCol>=0 ){
pE->op = TK_COLUMN;
pE->iColumn = iCol;
pE->iTable = iTable;
pE->iAgg = -1;
pOrderBy->a[i].done = 1;
}
if( iCol<0 && mustComplete ){
sqlite3ErrorMsg(pParse,
"ORDER BY term number %d does not match any result column", i+1);
nErr++;
break;
}
}
return nErr;
}
#endif /* #ifndef SQLITE_OMIT_COMPOUND_SELECT */
/*
** 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.
*/
Vdbe *sqlite3GetVdbe(Parse *pParse){
Vdbe *v = pParse->pVdbe;
if( v==0 ){
v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
}
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 = 0;
int iLimit = 0;
int iOffset;
int addr1, addr2;
/*
** "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.
*/
if( p->pLimit ){
p->iLimit = iLimit = pParse->nMem;
pParse->nMem += 2;
v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
sqlite3ExprCode(pParse, p->pLimit);
sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
sqlite3VdbeAddOp(v, OP_MemStore, iLimit, 0);
VdbeComment((v, "# LIMIT counter"));
sqlite3VdbeAddOp(v, OP_IfMemZero, iLimit, iBreak);
}
if( p->pOffset ){
p->iOffset = iOffset = pParse->nMem++;
v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
sqlite3ExprCode(pParse, p->pOffset);
sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
sqlite3VdbeAddOp(v, OP_MemStore, iOffset, p->pLimit==0);
VdbeComment((v, "# OFFSET counter"));
addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iOffset, 0);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
sqlite3VdbeJumpHere(v, addr1);
if( p->pLimit ){
sqlite3VdbeAddOp(v, OP_Add, 0, 0);
}
}
if( p->pLimit ){
addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iLimit, 0);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
sqlite3VdbeAddOp(v, OP_MemInt, -1, iLimit+1);
addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp(v, OP_MemStore, iLimit+1, 1);
VdbeComment((v, "# LIMIT+OFFSET"));
sqlite3VdbeJumpHere(v, addr2);
}
}
/*
** Allocate a virtual index to use for sorting.
*/
static void createSortingIndex(Parse *pParse, Select *p, ExprList *pOrderBy){
if( pOrderBy ){
int addr;
assert( pOrderBy->iECursor==0 );
pOrderBy->iECursor = pParse->nTab++;
addr = sqlite3VdbeAddOp(pParse->pVdbe, OP_OpenVirtual,
pOrderBy->iECursor, pOrderBy->nExpr+1);
assert( p->addrOpenVirt[2] == -1 );
p->addrOpenVirt[2] = addr;
}
}
#ifndef 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 ){
pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
}else{
pRet = 0;
}
if( pRet==0 ){
pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
}
return pRet;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** This routine is called to process a query that is really the union
** or intersection of two or more separate queries.
**
** "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 */
int eDest, /* \___ Store query results as specified */
int iParm, /* / by these two parameters. */
char *aff /* If eDest is SRT_Union, the affinity string */
){
int rc = SQLITE_OK; /* Success code from a subroutine */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
int nCol; /* Number of columns in the result set */
ExprList *pOrderBy; /* The ORDER BY clause on p */
int aSetP2[2]; /* Set P2 value of these op to number of columns */
int nSetP2 = 0; /* Number of slots in aSetP2[] used */
/* 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.
*/
if( p==0 || p->pPrior==0 ){
rc = 1;
goto multi_select_end;
}
pPrior = p->pPrior;
assert( pPrior->pRightmost!=pPrior );
assert( pPrior->pRightmost==p->pRightmost );
if( pPrior->pOrderBy ){
sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
selectOpName(p->op));
rc = 1;
goto multi_select_end;
}
if( pPrior->pLimit ){
sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before",
selectOpName(p->op));
rc = 1;
goto multi_select_end;
}
/* Make sure we have a valid query engine. If not, create a new one.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ){
rc = 1;
goto multi_select_end;
}
/* Create the destination temporary table if necessary
*/
if( eDest==SRT_VirtualTab ){
assert( p->pEList );
assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
aSetP2[nSetP2++] = sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, 0);
eDest = SRT_Table;
}
/* Generate code for the left and right SELECT statements.
*/
pOrderBy = p->pOrderBy;
switch( p->op ){
case TK_ALL: {
if( pOrderBy==0 ){
int addr = 0;
assert( !pPrior->pLimit );
pPrior->pLimit = p->pLimit;
pPrior->pOffset = p->pOffset;
rc = sqlite3Select(pParse, pPrior, eDest, iParm, 0, 0, 0, aff);
p->pLimit = 0;
p->pOffset = 0;
if( rc ){
goto multi_select_end;
}
p->pPrior = 0;
p->iLimit = pPrior->iLimit;
p->iOffset = pPrior->iOffset;
if( p->iLimit>=0 ){
addr = sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, 0);
VdbeComment((v, "# Jump ahead if LIMIT reached"));
}
rc = sqlite3Select(pParse, p, eDest, iParm, 0, 0, 0, aff);
p->pPrior = pPrior;
if( rc ){
goto multi_select_end;
}
if( addr ){
sqlite3VdbeJumpHere(v, addr);
}
break;
}
/* For UNION ALL ... ORDER BY fall through to the next case */
}
case TK_EXCEPT:
case TK_UNION: {
int unionTab; /* Cursor number of the temporary table holding result */
int 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;
priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
if( eDest==priorOp && pOrderBy==0 && !p->pLimit && !p->pOffset ){
/* We can reuse a temporary table generated by a SELECT to our
** right.
*/
unionTab = iParm;
}else{
/* We will need to create our own temporary table to hold the
** intermediate results.
*/
unionTab = pParse->nTab++;
if( pOrderBy && matchOrderbyToColumn(pParse, p, pOrderBy, unionTab,1) ){
rc = 1;
goto multi_select_end;
}
addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, unionTab, 0);
if( priorOp==SRT_Table ){
assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
aSetP2[nSetP2++] = addr;
}else{
assert( p->addrOpenVirt[0] == -1 );
p->addrOpenVirt[0] = addr;
p->pRightmost->usesVirt = 1;
}
createSortingIndex(pParse, p, pOrderBy);
assert( p->pEList );
}
/* Code the SELECT statements to our left
*/
assert( !pPrior->pOrderBy );
rc = sqlite3Select(pParse, pPrior, priorOp, unionTab, 0, 0, 0, aff);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT statement
*/
switch( p->op ){
case TK_EXCEPT: op = SRT_Except; break;
case TK_UNION: op = SRT_Union; break;
case TK_ALL: op = SRT_Table; break;
}
p->pPrior = 0;
p->pOrderBy = 0;
p->disallowOrderBy = pOrderBy!=0;
pLimit = p->pLimit;
p->pLimit = 0;
pOffset = p->pOffset;
p->pOffset = 0;
rc = sqlite3Select(pParse, p, op, unionTab, 0, 0, 0, aff);
p->pPrior = pPrior;
p->pOrderBy = pOrderBy;
sqlite3ExprDelete(p->pLimit);
p->pLimit = pLimit;
p->pOffset = pOffset;
p->iLimit = -1;
p->iOffset = -1;
if( rc ){
goto multi_select_end;
}
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
if( eDest!=priorOp || unionTab!=iParm ){
int iCont, iBreak, iStart;
assert( p->pEList );
if( eDest==SRT_Callback ){
Select *pFirst = p;
while( pFirst->pPrior ) pFirst = pFirst->pPrior;
generateColumnNames(pParse, 0, pFirst->pEList);
}
iBreak = sqlite3VdbeMakeLabel(v);
iCont = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp(v, OP_Rewind, unionTab, iBreak);
iStart = sqlite3VdbeCurrentAddr(v);
rc = selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
pOrderBy, -1, eDest, iParm,
iCont, iBreak, 0);
if( rc ){
rc = 1;
goto multi_select_end;
}
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp(v, OP_Next, unionTab, iStart);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp(v, OP_Close, unionTab, 0);
}
break;
}
case TK_INTERSECT: {
int tab1, tab2;
int iCont, iBreak, iStart;
Expr *pLimit, *pOffset;
int addr;
/* 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++;
if( pOrderBy && matchOrderbyToColumn(pParse,p,pOrderBy,tab1,1) ){
rc = 1;
goto multi_select_end;
}
createSortingIndex(pParse, p, pOrderBy);
addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, tab1, 0);
assert( p->addrOpenVirt[0] == -1 );
p->addrOpenVirt[0] = addr;
p->pRightmost->usesVirt = 1;
assert( p->pEList );
/* Code the SELECTs to our left into temporary table "tab1".
*/
rc = sqlite3Select(pParse, pPrior, SRT_Union, tab1, 0, 0, 0, aff);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT into temporary table "tab2"
*/
addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, tab2, 0);
assert( p->addrOpenVirt[1] == -1 );
p->addrOpenVirt[1] = addr;
p->pPrior = 0;
pLimit = p->pLimit;
p->pLimit = 0;
pOffset = p->pOffset;
p->pOffset = 0;
rc = sqlite3Select(pParse, p, SRT_Union, tab2, 0, 0, 0, aff);
p->pPrior = pPrior;
sqlite3ExprDelete(p->pLimit);
p->pLimit = pLimit;
p->pOffset = pOffset;
if( rc ){
goto multi_select_end;
}
/* Generate code to take the intersection of the two temporary
** tables.
*/
assert( p->pEList );
if( eDest==SRT_Callback ){
Select *pFirst = p;
while( pFirst->pPrior ) pFirst = pFirst->pPrior;
generateColumnNames(pParse, 0, pFirst->pEList);
}
iBreak = sqlite3VdbeMakeLabel(v);
iCont = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp(v, OP_Rewind, tab1, iBreak);
iStart = sqlite3VdbeAddOp(v, OP_RowKey, tab1, 0);
sqlite3VdbeAddOp(v, OP_NotFound, tab2, iCont);
rc = selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
pOrderBy, -1, eDest, iParm,
iCont, iBreak, 0);
if( rc ){
rc = 1;
goto multi_select_end;
}
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp(v, OP_Next, tab1, iStart);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp(v, OP_Close, tab2, 0);
sqlite3VdbeAddOp(v, OP_Close, tab1, 0);
break;
}
}
/* Make sure all SELECTs in the statement have the same number of elements
** in their result sets.
*/
assert( p->pEList && pPrior->pEList );
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;
}
/* Set the number of columns in temporary tables
*/
nCol = p->pEList->nExpr;
while( nSetP2 ){
sqlite3VdbeChangeP2(v, aSetP2[--nSetP2], nCol);
}
/* Compute collating sequences used by either the ORDER BY clause or
** by any temporary tables needed to implement the compound select.
** Attach the KeyInfo structure to all temporary tables. Invoke the
** ORDER BY processing if there is an ORDER BY clause.
**
** 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( pOrderBy || p->usesVirt ){
int i; /* Loop counter */
KeyInfo *pKeyInfo; /* Collating sequence for the result set */
Select *pLoop; /* For looping through SELECT statements */
CollSeq **apColl;
CollSeq **aCopy;
assert( p->pRightmost==p );
pKeyInfo = sqliteMalloc(sizeof(*pKeyInfo)+nCol*2*sizeof(CollSeq*) + nCol);
if( !pKeyInfo ){
rc = SQLITE_NOMEM;
goto multi_select_end;
}
pKeyInfo->enc = ENC(pParse->db);
pKeyInfo->nField = nCol;
for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
*apColl = multiSelectCollSeq(pParse, p, i);
if( 0==*apColl ){
*apColl = pParse->db->pDfltColl;
}
}
for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
for(i=0; i<2; i++){
int addr = pLoop->addrOpenVirt[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 */
assert( pLoop->addrOpenVirt[1]<0 );
break;
}
sqlite3VdbeChangeP2(v, addr, nCol);
sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO);
}
}
if( pOrderBy ){
struct ExprList_item *pOTerm = pOrderBy->a;
int nOrderByExpr = pOrderBy->nExpr;
int addr;
u8 *pSortOrder;
aCopy = &pKeyInfo->aColl[nCol];
pSortOrder = pKeyInfo->aSortOrder = (u8*)&aCopy[nCol];
memcpy(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*));
apColl = pKeyInfo->aColl;
for(i=0; i<nOrderByExpr; i++, pOTerm++, apColl++, pSortOrder++){
Expr *pExpr = pOTerm->pExpr;
char *zName = pOTerm->zName;
assert( pExpr->op==TK_COLUMN && pExpr->iColumn<nCol );
if( zName ){
*apColl = sqlite3LocateCollSeq(pParse, zName, -1);
}else{
*apColl = aCopy[pExpr->iColumn];
}
*pSortOrder = pOTerm->sortOrder;
}
assert( p->pRightmost==p );
assert( p->addrOpenVirt[2]>=0 );
addr = p->addrOpenVirt[2];
sqlite3VdbeChangeP2(v, addr, p->pEList->nExpr+2);
pKeyInfo->nField = nOrderByExpr;
sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
pKeyInfo = 0;
generateSortTail(pParse, p, v, p->pEList->nExpr, eDest, iParm);
}
sqliteFree(pKeyInfo);
}
multi_select_end:
return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
#ifndef SQLITE_OMIT_VIEW
/*
** 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 void substExprList(ExprList*,int,ExprList*); /* Forward Decl */
static void substSelect(Select *, int, ExprList *); /* Forward Decl */
static void substExpr(Expr *pExpr, int iTable, ExprList *pEList){
if( pExpr==0 ) return;
if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){
if( pExpr->iColumn<0 ){
pExpr->op = TK_NULL;
}else{
Expr *pNew;
assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 );
pNew = pEList->a[pExpr->iColumn].pExpr;
assert( pNew!=0 );
pExpr->op = pNew->op;
assert( pExpr->pLeft==0 );
pExpr->pLeft = sqlite3ExprDup(pNew->pLeft);
assert( pExpr->pRight==0 );
pExpr->pRight = sqlite3ExprDup(pNew->pRight);
assert( pExpr->pList==0 );
pExpr->pList = sqlite3ExprListDup(pNew->pList);
pExpr->iTable = pNew->iTable;
pExpr->iColumn = pNew->iColumn;
pExpr->iAgg = pNew->iAgg;
sqlite3TokenCopy(&pExpr->token, &pNew->token);
sqlite3TokenCopy(&pExpr->span, &pNew->span);
pExpr->pSelect = sqlite3SelectDup(pNew->pSelect);
pExpr->flags = pNew->flags;
}
}else{
substExpr(pExpr->pLeft, iTable, pEList);
substExpr(pExpr->pRight, iTable, pEList);
substSelect(pExpr->pSelect, iTable, pEList);
substExprList(pExpr->pList, iTable, pEList);
}
}
static void substExprList(ExprList *pList, int iTable, ExprList *pEList){
int i;
if( pList==0 ) return;
for(i=0; i<pList->nExpr; i++){
substExpr(pList->a[i].pExpr, iTable, pEList);
}
}
static void substSelect(Select *p, int iTable, ExprList *pEList){
if( !p ) return;
substExprList(p->pEList, iTable, pEList);
substExprList(p->pGroupBy, iTable, pEList);
substExprList(p->pOrderBy, iTable, pEList);
substExpr(p->pHaving, iTable, pEList);
substExpr(p->pWhere, iTable, pEList);
}
#endif /* !defined(SQLITE_OMIT_VIEW) */
#ifndef 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, or
** the subquery is not itself a join. (Ticket #306)
**
** (4) The subquery is not DISTINCT or the outer query is not a join.
**
** (5) The subquery is not DISTINCT or the outer query does not use
** aggregates.
**
** (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.
**
** (12) The subquery is not the right term of a LEFT OUTER JOIN or the
** subquery has no WHERE clause. (added by ticket #350)
**
** (13) The subquery and outer query do not both use LIMIT
**
** (14) The subquery does not use OFFSET
**
** 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(
Select *p, /* The parent or outer SELECT statement */
int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
int isAgg, /* True if outer SELECT uses aggregate functions */
int subqueryIsAgg /* True if the subquery uses aggregate functions */
){
Select *pSub; /* The inner query or "subquery" */
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 */
struct SrcList_item *pSubitem; /* The subquery */
/* Check to see if flattening is permitted. Return 0 if not.
*/
if( p==0 ) return 0;
pSrc = p->pSrc;
assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
pSubitem = &pSrc->a[iFrom];
pSub = pSubitem->pSelect;
assert( pSub!=0 );
if( isAgg && subqueryIsAgg ) return 0; /* Restriction (1) */
if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; /* Restriction (2) */
pSubSrc = pSub->pSrc;
assert( pSubSrc );
/* 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 && p->pLimit ) return 0; /* Restriction (13) */
if( pSub->pOffset ) return 0; /* Restriction (14) */
if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */
if( (pSub->isDistinct || pSub->pLimit)
&& (pSrc->nSrc>1 || isAgg) ){ /* Restrictions (4)(5)(8)(9) */
return 0;
}
if( p->isDistinct && subqueryIsAgg ) return 0; /* Restriction (6) */
if( (p->disallowOrderBy || p->pOrderBy) && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
/* 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.
*/
if( pSubSrc->nSrc>1 && iFrom>0 && (pSrc->a[iFrom-1].jointype & JT_OUTER)!=0 ){
return 0;
}
/* 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.
*/
if( iFrom>0 && (pSrc->a[iFrom-1].jointype & JT_OUTER)!=0
&& pSub->pWhere!=0 ){
return 0;
}
/* If we reach this point, it means flattening is permitted for the
** iFrom-th entry of the FROM clause in the outer query.
*/
/* Move 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.
*/
iParent = pSubitem->iCursor;
{
int nSubSrc = pSubSrc->nSrc;
int jointype = pSubitem->jointype;
sqlite3DeleteTable(0, pSubitem->pTab);
sqliteFree(pSubitem->zDatabase);
sqliteFree(pSubitem->zName);
sqliteFree(pSubitem->zAlias);
if( nSubSrc>1 ){
int extra = nSubSrc - 1;
for(i=1; i<nSubSrc; i++){
pSrc = sqlite3SrcListAppend(pSrc, 0, 0);
}
p->pSrc = pSrc;
for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){
pSrc->a[i] = pSrc->a[i-extra];
}
}
for(i=0; i<nSubSrc; i++){
pSrc->a[i+iFrom] = pSubSrc->a[i];
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
pSrc->a[iFrom+nSubSrc-1].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 = p->pEList;
for(i=0; i<pList->nExpr; i++){
Expr *pExpr;
if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){
pList->a[i].zName = sqliteStrNDup((char*)pExpr->span.z, pExpr->span.n);
}
}
substExprList(p->pEList, iParent, pSub->pEList);
if( isAgg ){
substExprList(p->pGroupBy, iParent, pSub->pEList);
substExpr(p->pHaving, iParent, pSub->pEList);
}
if( pSub->pOrderBy ){
assert( p->pOrderBy==0 );
p->pOrderBy = pSub->pOrderBy;
pSub->pOrderBy = 0;
}else if( p->pOrderBy ){
substExprList(p->pOrderBy, iParent, pSub->pEList);
}
if( pSub->pWhere ){
pWhere = sqlite3ExprDup(pSub->pWhere);
}else{
pWhere = 0;
}
if( subqueryIsAgg ){
assert( p->pHaving==0 );
p->pHaving = p->pWhere;
p->pWhere = pWhere;
substExpr(p->pHaving, iParent, pSub->pEList);
p->pHaving = sqlite3ExprAnd(p->pHaving, sqlite3ExprDup(pSub->pHaving));
assert( p->pGroupBy==0 );
p->pGroupBy = sqlite3ExprListDup(pSub->pGroupBy);
}else{
substExpr(p->pWhere, iParent, pSub->pEList);
p->pWhere = sqlite3ExprAnd(p->pWhere, pWhere);
}
/* The flattened query is distinct if either the inner or the
** outer query is distinct.
*/
p->isDistinct = p->isDistinct || pSub->isDistinct;
/*
** 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 ){
p->pLimit = pSub->pLimit;
pSub->pLimit = 0;
}
/* Finially, delete what is left of the subquery and return
** success.
*/
sqlite3SelectDelete(pSub);
return 1;
}
#endif /* SQLITE_OMIT_VIEW */
/*
** Analyze the SELECT statement passed in as an argument to see if it
** is a simple min() or max() query. If it is and this query can be
** satisfied using a single seek to the beginning or end of an index,
** then generate the code for this SELECT and return 1. If this is not a
** simple min() or max() query, then return 0;
**
** A simply min() or max() query looks like this:
**
** SELECT min(a) FROM table;
** SELECT max(a) FROM table;
**
** The query may have only a single table in its FROM argument. There
** can be no GROUP BY or HAVING or WHERE clauses. The result set must
** be the min() or max() of a single column of the table. The column
** in the min() or max() function must be indexed.
**
** The parameters to this routine are the same as for sqlite3Select().
** See the header comment on that routine for additional information.
*/
static int simpleMinMaxQuery(Parse *pParse, Select *p, int eDest, int iParm){
Expr *pExpr;
int iCol;
Table *pTab;
Index *pIdx;
int base;
Vdbe *v;
int seekOp;
ExprList *pEList, *pList, eList;
struct ExprList_item eListItem;
SrcList *pSrc;
int brk;
int iDb;
/* Check to see if this query is a simple min() or max() query. Return
** zero if it is not.
*/
if( p->pGroupBy || p->pHaving || p->pWhere ) return 0;
pSrc = p->pSrc;
if( pSrc->nSrc!=1 ) return 0;
pEList = p->pEList;
if( pEList->nExpr!=1 ) return 0;
pExpr = pEList->a[0].pExpr;
if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
pList = pExpr->pList;
if( pList==0 || pList->nExpr!=1 ) return 0;
if( pExpr->token.n!=3 ) return 0;
if( sqlite3StrNICmp((char*)pExpr->token.z,"min",3)==0 ){
seekOp = OP_Rewind;
}else if( sqlite3StrNICmp((char*)pExpr->token.z,"max",3)==0 ){
seekOp = OP_Last;
}else{
return 0;
}
pExpr = pList->a[0].pExpr;
if( pExpr->op!=TK_COLUMN ) return 0;
iCol = pExpr->iColumn;
pTab = pSrc->a[0].pTab;
/* If we get to here, it means the query is of the correct form.
** Check to make sure we have an index and make pIdx point to the
** appropriate index. If the min() or max() is on an INTEGER PRIMARY
** key column, no index is necessary so set pIdx to NULL. If no
** usable index is found, return 0.
*/
if( iCol<0 ){
pIdx = 0;
}else{
CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr);
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
assert( pIdx->nColumn>=1 );
if( pIdx->aiColumn[0]==iCol &&
0==sqlite3StrICmp(pIdx->azColl[0], pColl->zName) ){
break;
}
}
if( pIdx==0 ) return 0;
}
/* Identify column types if we will be using the callback. This
** step is skipped if the output is going to a table or a memory cell.
** The column names have already been generated in the calling function.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ) return 0;
/* If the output is destined for a temporary table, open that table.
*/
if( eDest==SRT_VirtualTab ){
sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, 1);
}
/* Generating code to find the min or the max. Basically all we have
** to do is find the first or the last entry in the chosen index. If
** the min() or max() is on the INTEGER PRIMARY KEY, then find the first
** or last entry in the main table.
*/
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
assert( iDb>=0 || pTab->isTransient );
sqlite3CodeVerifySchema(pParse, iDb);
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
base = pSrc->a[0].iCursor;
brk = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, brk);
if( pSrc->a[0].pSelect==0 ){
sqlite3OpenTable(pParse, base, iDb, pTab, OP_OpenRead);
}
if( pIdx==0 ){
sqlite3VdbeAddOp(v, seekOp, base, 0);
}else{
/* Even though the cursor used to open the index here is closed
** as soon as a single value has been read from it, allocate it
** using (pParse->nTab++) to prevent the cursor id from being
** reused. This is important for statements of the form
** "INSERT INTO x SELECT max() FROM x".
*/
int iIdx;
KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
iIdx = pParse->nTab++;
assert( pIdx->pSchema==pTab->pSchema );
sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
sqlite3VdbeOp3(v, OP_OpenRead, iIdx, pIdx->tnum,
(char*)pKey, P3_KEYINFO_HANDOFF);
if( seekOp==OP_Rewind ){
sqlite3VdbeAddOp(v, OP_Null, 0, 0);
sqlite3VdbeAddOp(v, OP_MakeRecord, 1, 0);
seekOp = OP_MoveGt;
}
sqlite3VdbeAddOp(v, seekOp, iIdx, 0);
sqlite3VdbeAddOp(v, OP_IdxRowid, iIdx, 0);
sqlite3VdbeAddOp(v, OP_Close, iIdx, 0);
sqlite3VdbeAddOp(v, OP_MoveGe, base, 0);
}
eList.nExpr = 1;
memset(&eListItem, 0, sizeof(eListItem));
eList.a = &eListItem;
eList.a[0].pExpr = pExpr;
selectInnerLoop(pParse, p, &eList, 0, 0, 0, -1, eDest, iParm, brk, brk, 0);
sqlite3VdbeResolveLabel(v, brk);
sqlite3VdbeAddOp(v, OP_Close, base, 0);
return 1;
}
/*
** Analyze and ORDER BY or GROUP BY clause in a SELECT statement. Return
** the number of errors seen.
**
** An ORDER BY or GROUP BY is a list of expressions. If any expression
** is an integer constant, then that expression is replaced by the
** corresponding entry in the result set.
*/
static int processOrderGroupBy(
NameContext *pNC, /* Name context of the SELECT statement. */
ExprList *pOrderBy, /* The ORDER BY or GROUP BY clause to be processed */
const char *zType /* Either "ORDER" or "GROUP", as appropriate */
){
int i;
ExprList *pEList = pNC->pEList; /* The result set of the SELECT */
Parse *pParse = pNC->pParse; /* The result set of the SELECT */
assert( pEList );
if( pOrderBy==0 ) return 0;
for(i=0; i<pOrderBy->nExpr; i++){
int iCol;
Expr *pE = pOrderBy->a[i].pExpr;
if( sqlite3ExprIsInteger(pE, &iCol) ){
if( iCol>0 && iCol<=pEList->nExpr ){
sqlite3ExprDelete(pE);
pE = pOrderBy->a[i].pExpr = sqlite3ExprDup(pEList->a[iCol-1].pExpr);
}else{
sqlite3ErrorMsg(pParse,
"%s BY column number %d out of range - should be "
"between 1 and %d", zType, iCol, pEList->nExpr);
return 1;
}
}
if( sqlite3ExprResolveNames(pNC, pE) ){
return 1;
}
}
return 0;
}
/*
** This routine resolves any names used in the result set of the
** supplied SELECT statement. If the SELECT statement being resolved
** is a sub-select, then pOuterNC is a pointer to the NameContext
** of the parent SELECT.
*/
int sqlite3SelectResolve(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
NameContext *pOuterNC /* The outer name context. May be NULL. */
){
ExprList *pEList; /* Result set. */
int i; /* For-loop variable used in multiple places */
NameContext sNC; /* Local name-context */
ExprList *pGroupBy; /* The group by clause */
/* If this routine has run before, return immediately. */
if( p->isResolved ){
assert( !pOuterNC );
return SQLITE_OK;
}
p->isResolved = 1;
/* If there have already been errors, do nothing. */
if( pParse->nErr>0 ){
return SQLITE_ERROR;
}
/* Prepare the select statement. This call will allocate all cursors
** required to handle the tables and subqueries in the FROM clause.
*/
if( prepSelectStmt(pParse, p) ){
return SQLITE_ERROR;
}
/* Resolve the expressions in the LIMIT and OFFSET clauses. These
** are not allowed to refer to any names, so pass an empty NameContext.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
if( sqlite3ExprResolveNames(&sNC, p->pLimit) ||
sqlite3ExprResolveNames(&sNC, p->pOffset) ){
return SQLITE_ERROR;
}
/* Set up the local name-context to pass to ExprResolveNames() to
** resolve the expression-list.
*/
sNC.allowAgg = 1;
sNC.pSrcList = p->pSrc;
sNC.pNext = pOuterNC;
/* Resolve names in the result set. */
pEList = p->pEList;
if( !pEList ) return SQLITE_ERROR;
for(i=0; i<pEList->nExpr; i++){
Expr *pX = pEList->a[i].pExpr;
if( sqlite3ExprResolveNames(&sNC, pX) ){
return SQLITE_ERROR;
}
}
/* If there are no aggregate functions in the result-set, and no GROUP BY
** expression, do not allow aggregates in any of the other expressions.
*/
assert( !p->isAgg );
pGroupBy = p->pGroupBy;
if( pGroupBy || sNC.hasAgg ){
p->isAgg = 1;
}else{
sNC.allowAgg = 0;
}
/* If a HAVING clause is present, then there must be a GROUP BY clause.
*/
if( p->pHaving && !pGroupBy ){
sqlite3ErrorMsg(pParse, "a GROUP BY clause is required before HAVING");
return SQLITE_ERROR;
}
/* Add the expression list to the name-context before parsing the
** other expressions in the SELECT statement. This is so that
** expressions in the WHERE clause (etc.) can refer to expressions by
** aliases in the result set.
**
** Minor point: If this is the case, then the expression will be
** re-evaluated for each reference to it.
*/
sNC.pEList = p->pEList;
if( sqlite3ExprResolveNames(&sNC, p->pWhere) ||
sqlite3ExprResolveNames(&sNC, p->pHaving) ||
processOrderGroupBy(&sNC, p->pOrderBy, "ORDER") ||
processOrderGroupBy(&sNC, pGroupBy, "GROUP")
){
return SQLITE_ERROR;
}
/* Make sure the GROUP BY clause does not contain aggregate functions.
*/
if( pGroupBy ){
struct ExprList_item *pItem;
for(i=0, pItem=pGroupBy->a; i<pGroupBy->nExpr; i++, pItem++){
if( ExprHasProperty(pItem->pExpr, EP_Agg) ){
sqlite3ErrorMsg(pParse, "aggregate functions are not allowed in "
"the GROUP BY clause");
return SQLITE_ERROR;
}
}
}
return SQLITE_OK;
}
/*
** 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;
struct AggInfo_func *pFunc;
if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){
return;
}
for(i=0; i<pAggInfo->nColumn; i++){
sqlite3VdbeAddOp(v, OP_MemNull, pAggInfo->aCol[i].iMem, 0);
}
for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
sqlite3VdbeAddOp(v, OP_MemNull, pFunc->iMem, 0);
if( pFunc->iDistinct>=0 ){
Expr *pE = pFunc->pExpr;
if( pE->pList==0 || pE->pList->nExpr!=1 ){
sqlite3ErrorMsg(pParse, "DISTINCT in aggregate must be followed "
"by an expression");
pFunc->iDistinct = -1;
}else{
KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->pList);
sqlite3VdbeOp3(v, OP_OpenVirtual, pFunc->iDistinct, 0,
(char*)pKeyInfo, P3_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;
struct AggInfo_func *pF;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
ExprList *pList = pF->pExpr->pList;
sqlite3VdbeOp3(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0,
(void*)pF->pFunc, P3_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;
struct AggInfo_func *pF;
struct AggInfo_col *pC;
pAggInfo->directMode = 1;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
int nArg;
int addrNext = 0;
ExprList *pList = pF->pExpr->pList;
if( pList ){
nArg = pList->nExpr;
sqlite3ExprCodeExprList(pParse, pList);
}else{
nArg = 0;
}
if( pF->iDistinct>=0 ){
addrNext = sqlite3VdbeMakeLabel(v);
assert( nArg==1 );
codeDistinct(v, pF->iDistinct, addrNext, 1);
}
if( pF->pFunc->needCollSeq ){
CollSeq *pColl = 0;
struct ExprList_item *pItem;
int j;
assert( pList!=0 ); /* pList!=0 if pF->pFunc->needCollSeq is true */
for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
}
if( !pColl ){
pColl = pParse->db->pDfltColl;
}
sqlite3VdbeOp3(v, OP_CollSeq, 0, 0, (char *)pColl, P3_COLLSEQ);
}
sqlite3VdbeOp3(v, OP_AggStep, pF->iMem, nArg, (void*)pF->pFunc, P3_FUNCDEF);
if( addrNext ){
sqlite3VdbeResolveLabel(v, addrNext);
}
}
for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
sqlite3ExprCode(pParse, pC->pExpr);
sqlite3VdbeAddOp(v, OP_MemStore, pC->iMem, 1);
}
pAggInfo->directMode = 0;
}
/*
** Generate code for the given SELECT statement.
**
** The results are distributed in various ways depending on the
** value of eDest and iParm.
**
** eDest Value Result
** ------------ -------------------------------------------
** SRT_Callback Invoke the callback for each row of the result.
**
** SRT_Mem Store first result in memory cell iParm
**
** SRT_Set Store results as keys of table iParm.
**
** SRT_Union Store results as a key in a temporary table iParm
**
** SRT_Except Remove results from the temporary table iParm.
**
** SRT_Table Store results in temporary table iParm
**
** The table above is incomplete. Additional eDist value have be added
** since this comment was written. See the selectInnerLoop() function for
** a complete listing of the allowed values of eDest and their meanings.
**
** 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.
**
** The pParent, parentTab, and *pParentAgg fields are filled in if this
** SELECT is a subquery. This routine may try to combine this SELECT
** with its parent to form a single flat query. In so doing, it might
** change the parent query from a non-aggregate to an aggregate query.
** For that reason, the pParentAgg flag is passed as a pointer, so it
** can be changed.
**
** Example 1: The meaning of the pParent parameter.
**
** SELECT * FROM t1 JOIN (SELECT x, count(*) FROM t2) JOIN t3;
** \ \_______ subquery _______/ /
** \ /
** \____________________ outer query ___________________/
**
** This routine is called for the outer query first. For that call,
** pParent will be NULL. During the processing of the outer query, this
** routine is called recursively to handle the subquery. For the recursive
** call, pParent will point to the outer query. Because the subquery is
** the second element in a three-way join, the parentTab parameter will
** be 1 (the 2nd value of a 0-indexed array.)
*/
int sqlite3Select(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
int eDest, /* How to dispose of the results */
int iParm, /* A parameter used by the eDest disposal method */
Select *pParent, /* Another SELECT for which this is a sub-query */
int parentTab, /* Index in pParent->pSrc of this query */
int *pParentAgg, /* True if pParent uses aggregate functions */
char *aff /* If eDest is SRT_Union, the affinity string */
){
int i, j; /* Loop counters */
WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */
Vdbe *v; /* The virtual machine under construction */
int isAgg; /* True for select lists like "count(*)" */
ExprList *pEList; /* List of columns to extract. */
SrcList *pTabList; /* 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 */
int 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_OpenVirtual instruction */
AggInfo sAggInfo; /* Information used by aggregate queries */
int iEnd; /* Address of the end of the query */
if( p==0 || sqlite3MallocFailed() || pParse->nErr ){
return 1;
}
if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
memset(&sAggInfo, 0, sizeof(sAggInfo));
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/* If there is are a sequence of queries, do the earlier ones first.
*/
if( p->pPrior ){
if( p->pRightmost==0 ){
Select *pLoop;
for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
pLoop->pRightmost = p;
}
}
return multiSelect(pParse, p, eDest, iParm, aff);
}
#endif
pOrderBy = p->pOrderBy;
if( IgnorableOrderby(eDest) ){
p->pOrderBy = 0;
}
if( sqlite3SelectResolve(pParse, p, 0) ){
goto select_end;
}
p->pOrderBy = pOrderBy;
/* Make local copies of the parameters for this query.
*/
pTabList = p->pSrc;
pWhere = p->pWhere;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
isAgg = p->isAgg;
isDistinct = p->isDistinct;
pEList = p->pEList;
if( pEList==0 ) goto select_end;
/*
** Do not even attempt to generate any code if we have already seen
** errors before this routine starts.
*/
if( pParse->nErr>0 ) goto select_end;
/* If writing to memory or generating a set
** only a single column may be output.
*/
#ifndef SQLITE_OMIT_SUBQUERY
if( (eDest==SRT_Mem || eDest==SRT_Set) && pEList->nExpr>1 ){
sqlite3ErrorMsg(pParse, "only a single result allowed for "
"a SELECT that is part of an expression");
goto select_end;
}
#endif
/* ORDER BY is ignored for some destinations.
*/
if( IgnorableOrderby(eDest) ){
pOrderBy = 0;
}
/* Begin generating code.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ) goto select_end;
/* Generate code for all sub-queries in the FROM clause
*/
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
for(i=0; i<pTabList->nSrc; i++){
const char *zSavedAuthContext = 0;
int needRestoreContext;
struct SrcList_item *pItem = &pTabList->a[i];
if( pItem->pSelect==0 || pItem->isPopulated ) continue;
if( pItem->zName!=0 ){
zSavedAuthContext = pParse->zAuthContext;
pParse->zAuthContext = pItem->zName;
needRestoreContext = 1;
}else{
needRestoreContext = 0;
}
sqlite3Select(pParse, pItem->pSelect, SRT_VirtualTab,
pItem->iCursor, p, i, &isAgg, 0);
if( needRestoreContext ){
pParse->zAuthContext = zSavedAuthContext;
}
pTabList = p->pSrc;
pWhere = p->pWhere;
if( !IgnorableOrderby(eDest) ){
pOrderBy = p->pOrderBy;
}
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
isDistinct = p->isDistinct;
}
#endif
/* Check for the special case of a min() or max() function by itself
** in the result set.
*/
if( simpleMinMaxQuery(pParse, p, eDest, iParm) ){
rc = 0;
goto select_end;
}
/* Check to see if this is a subquery that can be "flattened" into its parent.
** If flattening is a possiblity, do so and return immediately.
*/
#ifndef SQLITE_OMIT_VIEW
if( pParent && pParentAgg &&
flattenSubquery(pParent, parentTab, *pParentAgg, isAgg) ){
if( isAgg ) *pParentAgg = 1;
goto select_end;
}
#endif
/* If there is an ORDER BY clause, resolve any collation sequences
** names that have been explicitly specified and create a sorting index.
**
** 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_OpenVirtual 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 ){
struct ExprList_item *pTerm;
KeyInfo *pKeyInfo;
for(i=0, pTerm=pOrderBy->a; i<pOrderBy->nExpr; i++, pTerm++){
if( pTerm->zName ){
pTerm->pExpr->pColl = sqlite3LocateCollSeq(pParse, pTerm->zName, -1);
}
}
if( pParse->nErr ){
goto select_end;
}
pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
pOrderBy->iECursor = pParse->nTab++;
p->addrOpenVirt[2] = addrSortIndex =
sqlite3VdbeOp3(v, OP_OpenVirtual, pOrderBy->iECursor, pOrderBy->nExpr+2,
(char*)pKeyInfo, P3_KEYINFO_HANDOFF);
}else{
addrSortIndex = -1;
}
/* If the output is destined for a temporary table, open that table.
*/
if( eDest==SRT_VirtualTab ){
sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, pEList->nExpr);
}
/* Set the limiter.
*/
iEnd = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iEnd);
/* Open a virtual index to use for the distinct set.
*/
if( isDistinct ){
KeyInfo *pKeyInfo;
distinct = pParse->nTab++;
pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
sqlite3VdbeOp3(v, OP_OpenVirtual, distinct, 0,
(char*)pKeyInfo, P3_KEYINFO_HANDOFF);
}else{
distinct = -1;
}
/* Aggregate and non-aggregate queries are handled differently */
if( !isAgg && pGroupBy==0 ){
/* This case is for non-aggregate queries
** Begin the database scan
*/
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy);
if( pWInfo==0 ) goto select_end;
/* If sorting index that was created by a prior OP_OpenVirtual
** instruction ended up not being needed, then change the OP_OpenVirtual
** into an OP_Noop.
*/
if( addrSortIndex>=0 && pOrderBy==0 ){
sqlite3VdbeChangeToNoop(v, addrSortIndex, 1);
p->addrOpenVirt[2] = -1;
}
/* Use the standard inner loop
*/
if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
iParm, pWInfo->iContinue, pWInfo->iBreak, aff) ){
goto select_end;
}
/* 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 GROUP BY order */
/* The following variables hold addresses or labels for parts of the
** virtual machine program we are putting together */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int addrSetAbort; /* Set the abort flag and return */
int addrInitializeLoop; /* Start of code that initializes the input loop */
int addrTopOfLoop; /* Top of the input loop */
int addrGroupByChange; /* Code that runs when any GROUP BY term changes */
int addrProcessRow; /* Code to process a single input row */
int addrEnd; /* End of all processing */
int addrSortingIdx; /* The OP_OpenVirtual for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
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.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
sNC.pAggInfo = &sAggInfo;
sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
sAggInfo.pGroupBy = pGroupBy;
if( sqlite3ExprAnalyzeAggList(&sNC, pEList) ){
goto select_end;
}
if( sqlite3ExprAnalyzeAggList(&sNC, pOrderBy) ){
goto select_end;
}
if( pHaving && sqlite3ExprAnalyzeAggregates(&sNC, pHaving) ){
goto select_end;
}
sAggInfo.nAccumulator = sAggInfo.nColumn;
for(i=0; i<sAggInfo.nFunc; i++){
if( sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->pList) ){
goto select_end;
}
}
if( sqlite3MallocFailed() ) goto select_end;
/* Processing for aggregates with GROUP BY is very different and
** much more complex tha aggregates without a GROUP BY.
*/
if( pGroupBy ){
KeyInfo *pKeyInfo; /* Keying information for the group by clause */
/* Create labels that we will be needing
*/
addrInitializeLoop = sqlite3VdbeMakeLabel(v);
addrGroupByChange = sqlite3VdbeMakeLabel(v);
addrProcessRow = sqlite3VdbeMakeLabel(v);
/* 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 OpenVirtual instruction
** will be converted into a Noop.
*/
sAggInfo.sortingIdx = pParse->nTab++;
pKeyInfo = keyInfoFromExprList(pParse, pGroupBy);
addrSortingIdx =
sqlite3VdbeOp3(v, OP_OpenVirtual, sAggInfo.sortingIdx,
sAggInfo.nSortingColumn,
(char*)pKeyInfo, P3_KEYINFO_HANDOFF);
/* Initialize memory locations used by GROUP BY aggregate processing
*/
iUseFlag = pParse->nMem++;
iAbortFlag = pParse->nMem++;
iAMem = pParse->nMem;
pParse->nMem += pGroupBy->nExpr;
iBMem = pParse->nMem;
pParse->nMem += pGroupBy->nExpr;
sqlite3VdbeAddOp(v, OP_MemInt, 0, iAbortFlag);
VdbeComment((v, "# clear abort flag"));
sqlite3VdbeAddOp(v, OP_MemInt, 0, iUseFlag);
VdbeComment((v, "# indicate accumulator empty"));
sqlite3VdbeAddOp(v, OP_Goto, 0, addrInitializeLoop);
/* 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);
sqlite3VdbeAddOp(v, OP_MemInt, 1, iAbortFlag);
VdbeComment((v, "# set abort flag"));
sqlite3VdbeAddOp(v, OP_Return, 0, 0);
addrOutputRow = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp(v, OP_IfMemPos, iUseFlag, addrOutputRow+2);
VdbeComment((v, "# Groupby result generator entry point"));
sqlite3VdbeAddOp(v, OP_Return, 0, 0);
finalizeAggFunctions(pParse, &sAggInfo);
if( pHaving ){
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, 1);
}
rc = selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
distinct, eDest, iParm,
addrOutputRow+1, addrSetAbort, aff);
if( rc ){
goto select_end;
}
sqlite3VdbeAddOp(v, OP_Return, 0, 0);
VdbeComment((v, "# end groupby result generator"));
/* Generate a subroutine that will reset the group-by accumulator
*/
addrReset = sqlite3VdbeCurrentAddr(v);
resetAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp(v, OP_Return, 0, 0);
/* 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.
*/
sqlite3VdbeResolveLabel(v, addrInitializeLoop);
sqlite3VdbeAddOp(v, OP_Gosub, 0, addrReset);
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy);
if( pWInfo==0 ) goto select_end;
if( pGroupBy==0 ){
/* The optimizer is able to deliver rows in group by order so
** we do not have to sort. The OP_OpenVirtual 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
*/
groupBySort = 1;
sqlite3ExprCodeExprList(pParse, pGroupBy);
sqlite3VdbeAddOp(v, OP_Sequence, sAggInfo.sortingIdx, 0);
j = pGroupBy->nExpr+1;
for(i=0; i<sAggInfo.nColumn; i++){
struct AggInfo_col *pCol = &sAggInfo.aCol[i];
if( pCol->iSorterColumn<j ) continue;
if( pCol->iColumn<0 ){
sqlite3VdbeAddOp(v, OP_Rowid, pCol->iTable, 0);
}else{
sqlite3VdbeAddOp(v, OP_Column, pCol->iTable, pCol->iColumn);
}
j++;
}
sqlite3VdbeAddOp(v, OP_MakeRecord, j, 0);
sqlite3VdbeAddOp(v, OP_IdxInsert, sAggInfo.sortingIdx, 0);
sqlite3WhereEnd(pWInfo);
sqlite3VdbeAddOp(v, OP_Sort, sAggInfo.sortingIdx, addrEnd);
VdbeComment((v, "# GROUP BY sort"));
sAggInfo.useSortingIdx = 1;
}
/* 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);
for(j=0; j<pGroupBy->nExpr; j++){
if( groupBySort ){
sqlite3VdbeAddOp(v, OP_Column, sAggInfo.sortingIdx, j);
}else{
sAggInfo.directMode = 1;
sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr);
}
sqlite3VdbeAddOp(v, OP_MemStore, iBMem+j, j<pGroupBy->nExpr-1);
}
for(j=pGroupBy->nExpr-1; j>=0; j--){
if( j<pGroupBy->nExpr-1 ){
sqlite3VdbeAddOp(v, OP_MemLoad, iBMem+j, 0);
}
sqlite3VdbeAddOp(v, OP_MemLoad, iAMem+j, 0);
if( j==0 ){
sqlite3VdbeAddOp(v, OP_Eq, 0x200, addrProcessRow);
}else{
sqlite3VdbeAddOp(v, OP_Ne, 0x200, addrGroupByChange);
}
sqlite3VdbeChangeP3(v, -1, (void*)pKeyInfo->aColl[j], P3_COLLSEQ);
}
/* Generate code that runs whenever the GROUP BY changes.
** Change 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.
*/
sqlite3VdbeResolveLabel(v, addrGroupByChange);
for(j=0; j<pGroupBy->nExpr; j++){
sqlite3VdbeAddOp(v, OP_MemMove, iAMem+j, iBMem+j);
}
sqlite3VdbeAddOp(v, OP_Gosub, 0, addrOutputRow);
VdbeComment((v, "# output one row"));
sqlite3VdbeAddOp(v, OP_IfMemPos, iAbortFlag, addrEnd);
VdbeComment((v, "# check abort flag"));
sqlite3VdbeAddOp(v, OP_Gosub, 0, addrReset);
VdbeComment((v, "# reset accumulator"));
/* Update the aggregate accumulators based on the content of
** the current row
*/
sqlite3VdbeResolveLabel(v, addrProcessRow);
updateAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp(v, OP_MemInt, 1, iUseFlag);
VdbeComment((v, "# indicate data in accumulator"));
/* End of the loop
*/
if( groupBySort ){
sqlite3VdbeAddOp(v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop);
}else{
sqlite3WhereEnd(pWInfo);
sqlite3VdbeChangeToNoop(v, addrSortingIdx, 1);
}
/* Output the final row of result
*/
sqlite3VdbeAddOp(v, OP_Gosub, 0, addrOutputRow);
VdbeComment((v, "# output final row"));
} /* endif pGroupBy */
else {
/* 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, 0);
if( pWInfo==0 ) goto select_end;
updateAccumulator(pParse, &sAggInfo);
sqlite3WhereEnd(pWInfo);
finalizeAggFunctions(pParse, &sAggInfo);
pOrderBy = 0;
if( pHaving ){
sqlite3ExprIfFalse(pParse, pHaving, addrEnd, 1);
}
selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1,
eDest, iParm, addrEnd, addrEnd, aff);
}
sqlite3VdbeResolveLabel(v, addrEnd);
} /* endif aggregate query */
/* 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 ){
generateSortTail(pParse, p, v, pEList->nExpr, eDest, iParm);
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If this was a subquery, we have now converted the subquery into a
** temporary table. So set the SrcList_item.isPopulated flag to prevent
** this subquery from being evaluated again and to force the use of
** the temporary table.
*/
if( pParent ){
assert( pParent->pSrc->nSrc>parentTab );
assert( pParent->pSrc->a[parentTab].pSelect==p );
pParent->pSrc->a[parentTab].isPopulated = 1;
}
#endif
/* 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:
/* Identify column names if we will be using them in a callback. This
** step is skipped if the output is going to some other destination.
*/
if( rc==SQLITE_OK && eDest==SRT_Callback ){
generateColumnNames(pParse, pTabList, pEList);
}
sqliteFree(sAggInfo.aCol);
sqliteFree(sAggInfo.aFunc);
return rc;
}