/*
** Copyright (c) 1999, 2000 D. Richard Hipp
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of the GNU General Public
** License as published by the Free Software Foundation; either
** version 2 of the License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
** General Public License for more details.
**
** You should have received a copy of the GNU General Public
** License along with this library; if not, write to the
** Free Software Foundation, Inc., 59 Temple Place - Suite 330,
** Boston, MA 02111-1307, USA.
**
** Author contact information:
** drh@hwaci.com
** http://www.hwaci.com/drh/
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements.
**
** $Id: select.c,v 1.12 2000/06/06 18:00:16 drh Exp $
*/
#include "sqliteInt.h"
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqliteSelectNew(
ExprList *pEList,
IdList *pSrc,
Expr *pWhere,
ExprList *pGroupBy,
Expr *pHaving,
ExprList *pOrderBy,
int isDistinct
){
Select *pNew;
pNew = sqliteMalloc( sizeof(*pNew) );
if( pNew==0 ) return 0;
pNew->pEList = pEList;
pNew->pSrc = pSrc;
pNew->pWhere = pWhere;
pNew->pGroupBy = pGroupBy;
pNew->pHaving = pHaving;
pNew->pOrderBy = pOrderBy;
pNew->isDistinct = isDistinct;
return pNew;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqliteSelectDelete(Select *p){
sqliteExprListDelete(p->pEList);
sqliteIdListDelete(p->pSrc);
sqliteExprDelete(p->pWhere);
sqliteExprListDelete(p->pGroupBy);
sqliteExprDelete(p->pHaving);
sqliteExprListDelete(p->pOrderBy);
sqliteFree(p);
}
/*
** Delete the aggregate information from the parse structure.
*/
void sqliteParseInfoReset(Parse *pParse){
sqliteFree(pParse->aAgg);
pParse->aAgg = 0;
pParse->nAgg = 0;
pParse->iAggCount = -1;
pParse->useAgg = 0;
}
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
*/
static int selectInnerLoop(
Parse *pParse, /* The parser context */
ExprList *pEList, /* List of values being extracted */
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 */
){
Vdbe *v = pParse->pVdbe;
int i;
/* Pull the requested fields.
*/
for(i=0; i<pEList->nExpr; i++){
sqliteExprCode(pParse, pEList->a[i].pExpr);
}
/* If the current result is not distinct, skip the rest
** of the processing for the current row.
*/
if( distinct>=0 ){
int lbl = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_MakeKey, pEList->nExpr, 1, 0, 0);
sqliteVdbeAddOp(v, OP_Distinct, distinct, lbl, 0, 0);
sqliteVdbeAddOp(v, OP_Pop, pEList->nExpr+1, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, iContinue, 0, 0);
sqliteVdbeAddOp(v, OP_String, 0, 0, "", lbl);
sqliteVdbeAddOp(v, OP_Put, distinct, 0, 0, 0);
}
/* If there is an ORDER BY clause, then store the results
** in a sorter.
*/
if( pOrderBy ){
char *zSortOrder;
sqliteVdbeAddOp(v, OP_SortMakeRec, pEList->nExpr, 0, 0, 0);
zSortOrder = sqliteMalloc( pOrderBy->nExpr + 1 );
if( zSortOrder==0 ) return 1;
for(i=0; i<pOrderBy->nExpr; i++){
zSortOrder[i] = pOrderBy->a[i].idx ? '-' : '+';
sqliteExprCode(pParse, pOrderBy->a[i].pExpr);
}
zSortOrder[pOrderBy->nExpr] = 0;
sqliteVdbeAddOp(v, OP_SortMakeKey, pOrderBy->nExpr, 0, zSortOrder, 0);
sqliteVdbeAddOp(v, OP_SortPut, 0, 0, 0, 0);
}else
/* If we are writing to a table, then write the results to the table.
*/
if( eDest==SRT_Table ){
sqliteVdbeAddOp(v, OP_MakeRecord, pEList->nExpr, 0, 0, 0);
sqliteVdbeAddOp(v, OP_New, iParm, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Pull, 1, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Put, iParm, 0, 0, 0);
}else
/* 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.
*/
if( eDest==SRT_Set ){
assert( pEList->nExpr==1 );
sqliteVdbeAddOp(v, OP_String, 0, 0, "", 0);
sqliteVdbeAddOp(v, OP_Put, iParm, 0, 0, 0);
}else
/* 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.
*/
if( eDest==SRT_Mem ){
sqliteVdbeAddOp(v, OP_MemStore, iParm, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, iBreak, 0, 0);
}else
/* If none of the above, send the data to the callback function.
*/
{
sqliteVdbeAddOp(v, OP_Callback, pEList->nExpr, 0, 0, 0);
}
return 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 a table with cursor iParm
**
** SRT_Table Store results in a regular table with cursor iParm
**
** 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.
*/
int sqliteSelect(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
int eDest, /* One of SRT_Callback, SRT_Mem, SRT_Set, SRT_Table */
int iParm /* Save result in this memory location, if >=0 */
){
int i, j;
WhereInfo *pWInfo;
Vdbe *v;
int isAgg = 0; /* True for select lists like "count(*)" */
ExprList *pEList; /* List of fields to extract. NULL means "*" */
IdList *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 */
pEList = p->pEList;
pTabList = p->pSrc;
pWhere = p->pWhere;
pOrderBy = p->pOrderBy;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
isDistinct = p->isDistinct;
/*
** Do not even attempt to generate any code if we have already seen
** errors before this routine starts.
*/
if( pParse->nErr>0 ) return 0;
sqliteParseInfoReset(pParse);
/* Look up every table in the table list.
*/
for(i=0; i<pTabList->nId; i++){
pTabList->a[i].pTab = sqliteFindTable(pParse->db, pTabList->a[i].zName);
if( pTabList->a[i].pTab==0 ){
sqliteSetString(&pParse->zErrMsg, "no such table: ",
pTabList->a[i].zName, 0);
pParse->nErr++;
return 1;
}
}
/* Allocate a temporary table to use for the DISTINCT set, if
** necessary. This must be done early to allocate the cursor before
** any calls to sqliteExprResolveIds().
*/
if( isDistinct ){
distinct = pParse->nTab++;
}else{
distinct = -1;
}
/* If the list of fields to retrieve is "*" then replace it with
** a list of all fields from all tables.
*/
if( pEList==0 ){
for(i=0; i<pTabList->nId; i++){
Table *pTab = pTabList->a[i].pTab;
for(j=0; j<pTab->nCol; j++){
Expr *pExpr = sqliteExpr(TK_FIELD, 0, 0, 0);
pExpr->iTable = i + pParse->nTab;
pExpr->iField = j;
pEList = sqliteExprListAppend(pEList, pExpr, 0);
}
}
}
/* If writing to memory or generating a set
** only a single column may be output.
*/
if( (eDest==SRT_Mem || eDest==SRT_Set) && pEList->nExpr>1 ){
sqliteSetString(&pParse->zErrMsg, "only a single result allowed for "
"a SELECT that is part of an expression", 0);
pParse->nErr++;
return 1;
}
/* ORDER BY is ignored if we are not sending the result to a callback.
*/
if( eDest!=SRT_Callback ){
pOrderBy = 0;
}
/* Allocate cursors for "expr IN (SELECT ...)" constructs.
*/
for(i=0; i<pEList->nExpr; i++){
sqliteExprResolveInSelect(pParse, pEList->a[i].pExpr);
}
if( pWhere ) sqliteExprResolveInSelect(pParse, pWhere);
if( pOrderBy ){
for(i=0; i<pOrderBy->nExpr; i++){
sqliteExprResolveInSelect(pParse, pOrderBy->a[i].pExpr);
}
}
if( pGroupBy ){
for(i=0; i<pGroupBy->nExpr; i++){
sqliteExprResolveInSelect(pParse, pGroupBy->a[i].pExpr);
}
}
if( pHaving ) sqliteExprResolveInSelect(pParse, pHaving);
/* Resolve the field names and do a semantics check on all the expressions.
*/
for(i=0; i<pEList->nExpr; i++){
if( sqliteExprResolveIds(pParse, pTabList, pEList->a[i].pExpr) ){
return 1;
}
if( sqliteExprCheck(pParse, pEList->a[i].pExpr, 1, &isAgg) ){
return 1;
}
}
if( pWhere ){
if( sqliteExprResolveIds(pParse, pTabList, pWhere) ){
return 1;
}
if( sqliteExprCheck(pParse, pWhere, 0, 0) ){
return 1;
}
}
if( pOrderBy ){
for(i=0; i<pOrderBy->nExpr; i++){
Expr *pE = pOrderBy->a[i].pExpr;
if( sqliteExprResolveIds(pParse, pTabList, pE) ){
return 1;
}
if( sqliteExprCheck(pParse, pE, isAgg, 0) ){
return 1;
}
}
}
if( pGroupBy ){
for(i=0; i<pGroupBy->nExpr; i++){
Expr *pE = pGroupBy->a[i].pExpr;
if( sqliteExprResolveIds(pParse, pTabList, pE) ){
return 1;
}
if( sqliteExprCheck(pParse, pE, isAgg, 0) ){
return 1;
}
}
}
if( pHaving ){
if( pGroupBy==0 ){
sqliteSetString(&pParse->zErrMsg, "a GROUP BY clause is required "
"before HAVING", 0);
pParse->nErr++;
return 1;
}
if( sqliteExprResolveIds(pParse, pTabList, pHaving) ){
return 1;
}
if( sqliteExprCheck(pParse, pHaving, isAgg, 0) ){
return 1;
}
}
/* Do an analysis of aggregate expressions.
*/
if( isAgg ){
for(i=0; i<pEList->nExpr; i++){
if( sqliteExprAnalyzeAggregates(pParse, pEList->a[i].pExpr) ){
return 1;
}
}
if( pGroupBy ){
for(i=0; i<pGroupBy->nExpr; i++){
if( sqliteExprAnalyzeAggregates(pParse, pGroupBy->a[i].pExpr) ){
return 1;
}
}
}
if( pHaving && sqliteExprAnalyzeAggregates(pParse, pHaving) ){
return 1;
}
}
/* Begin generating code.
*/
v = pParse->pVdbe;
if( v==0 ){
v = pParse->pVdbe = sqliteVdbeCreate(pParse->db->pBe);
}
if( v==0 ){
sqliteSetString(&pParse->zErrMsg, "out of memory", 0);
pParse->nErr++;
return 1;
}
if( pOrderBy ){
sqliteVdbeAddOp(v, OP_SortOpen, 0, 0, 0, 0);
}
/* Identify column names if we will be using in the callback. This
** step is skipped if the output is going to a table or a memory cell.
*/
if( eDest==SRT_Callback ){
sqliteVdbeAddOp(v, OP_ColumnCount, pEList->nExpr, 0, 0, 0);
for(i=0; i<pEList->nExpr; i++){
Expr *p;
if( pEList->a[i].zName ){
char *zName = pEList->a[i].zName;
int addr = sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
if( zName[0]=='\'' || zName[0]=='"' ){
sqliteVdbeDequoteP3(v, addr);
}
continue;
}
p = pEList->a[i].pExpr;
if( p->op!=TK_FIELD ){
char zName[30];
sprintf(zName, "field%d", i+1);
sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
}else{
if( pTabList->nId>1 ){
char *zName = 0;
Table *pTab = pTabList->a[p->iTable].pTab;
char *zTab;
zTab = pTabList->a[p->iTable].zAlias;
if( zTab==0 ) zTab = pTab->zName;
sqliteSetString(&zName, zTab, ".", pTab->aCol[p->iField].zName, 0);
sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
sqliteFree(zName);
}else{
Table *pTab = pTabList->a[0].pTab;
char *zName = pTab->aCol[p->iField].zName;
sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
}
}
}
}
/* Reset the aggregator
*/
if( isAgg ){
sqliteVdbeAddOp(v, OP_AggReset, 0, pParse->nAgg, 0, 0);
}
/* Initialize the memory cell to NULL
*/
if( eDest==SRT_Mem ){
sqliteVdbeAddOp(v, OP_Null, 0, 0, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, iParm, 0, 0, 0);
}
/* Begin the database scan
*/
if( isDistinct ){
sqliteVdbeAddOp(v, OP_Open, distinct, 1, 0, 0);
}
pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 0);
if( pWInfo==0 ) return 1;
/* Use the standard inner loop if we are not dealing with
** aggregates
*/
if( !isAgg ){
if( selectInnerLoop(pParse, pEList, pOrderBy, distinct, eDest, iParm,
pWInfo->iContinue, pWInfo->iBreak) ){
return 1;
}
}
/* If we are dealing with aggregates, then to the special aggregate
** processing.
*/
else{
int doFocus;
if( pGroupBy ){
for(i=0; i<pGroupBy->nExpr; i++){
sqliteExprCode(pParse, pGroupBy->a[i].pExpr);
}
sqliteVdbeAddOp(v, OP_MakeKey, pGroupBy->nExpr, 0, 0, 0);
doFocus = 1;
}else{
doFocus = 0;
for(i=0; i<pParse->nAgg; i++){
if( !pParse->aAgg[i].isAgg ){
doFocus = 1;
break;
}
}
if( doFocus ){
sqliteVdbeAddOp(v, OP_String, 0, 0, "", 0);
}
}
if( doFocus ){
int lbl1 = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_AggFocus, 0, lbl1, 0, 0);
for(i=0; i<pParse->nAgg; i++){
if( pParse->aAgg[i].isAgg ) continue;
sqliteExprCode(pParse, pParse->aAgg[i].pExpr);
sqliteVdbeAddOp(v, OP_AggSet, 0, i, 0, 0);
}
sqliteVdbeResolveLabel(v, lbl1);
}
for(i=0; i<pParse->nAgg; i++){
Expr *pE;
int op;
if( !pParse->aAgg[i].isAgg ) continue;
pE = pParse->aAgg[i].pExpr;
if( pE==0 ){
sqliteVdbeAddOp(v, OP_AggIncr, 1, i, 0, 0);
continue;
}
assert( pE->op==TK_AGG_FUNCTION );
assert( pE->pList!=0 && pE->pList->nExpr==1 );
sqliteExprCode(pParse, pE->pList->a[0].pExpr);
sqliteVdbeAddOp(v, OP_AggGet, 0, i, 0, 0);
switch( pE->iField ){
case FN_Min: op = OP_Min; break;
case FN_Max: op = OP_Max; break;
case FN_Avg: op = OP_Add; break;
case FN_Sum: op = OP_Add; break;
}
sqliteVdbeAddOp(v, op, 0, 0, 0, 0);
sqliteVdbeAddOp(v, OP_AggSet, 0, i, 0, 0);
}
}
/* End the database scan loop.
*/
sqliteWhereEnd(pWInfo);
/* If we are processing aggregates, we need to set up a second loop
** over all of the aggregate values and process them.
*/
if( isAgg ){
int endagg = sqliteVdbeMakeLabel(v);
int startagg;
startagg = sqliteVdbeAddOp(v, OP_AggNext, 0, endagg, 0, 0);
pParse->useAgg = 1;
if( pHaving ){
sqliteExprIfFalse(pParse, pHaving, startagg);
}
if( selectInnerLoop(pParse, pEList, pOrderBy, distinct, eDest, iParm,
startagg, endagg) ){
return 1;
}
sqliteVdbeAddOp(v, OP_Goto, 0, startagg, 0, 0);
sqliteVdbeAddOp(v, OP_Noop, 0, 0, 0, endagg);
pParse->useAgg = 0;
}
/* 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 ){
int end = sqliteVdbeMakeLabel(v);
int addr;
sqliteVdbeAddOp(v, OP_Sort, 0, 0, 0, 0);
addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end, 0, 0);
sqliteVdbeAddOp(v, OP_SortCallback, pEList->nExpr, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, addr, 0, 0);
sqliteVdbeAddOp(v, OP_SortClose, 0, 0, 0, end);
}
return 0;
}