/*
** 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 1.32 2001/09/13 13:46:57 drh Exp $
*/
#include "sqliteInt.h"
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqliteSelectNew(
ExprList *pEList, /* which columns to include in the result */
IdList *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 */
){
Select *pNew;
pNew = sqliteMalloc( sizeof(*pNew) );
if( pNew==0 ){
sqliteExprListDelete(pEList);
sqliteIdListDelete(pSrc);
sqliteExprDelete(pWhere);
sqliteExprListDelete(pGroupBy);
sqliteExprDelete(pHaving);
sqliteExprListDelete(pOrderBy);
}else{
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;
}
return pNew;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqliteSelectDelete(Select *p){
if( p==0 ) return;
sqliteExprListDelete(p->pEList);
sqliteIdListDelete(p->pSrc);
sqliteExprDelete(p->pWhere);
sqliteExprListDelete(p->pGroupBy);
sqliteExprDelete(p->pHaving);
sqliteExprListDelete(p->pOrderBy);
sqliteSelectDelete(p->pPrior);
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.
**
** The pEList is used to determine the values for each column in the
** result row. Except if pEList==NULL, then we just read nColumn
** elements from the srcTab table.
*/
static int selectInnerLoop(
Parse *pParse, /* The parser context */
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 */
){
Vdbe *v = pParse->pVdbe;
int i;
if( v==0 ) return 0;
/* Pull the requested columns.
*/
if( pEList ){
for(i=0; i<pEList->nExpr; i++){
sqliteExprCode(pParse, pEList->a[i].pExpr);
}
nColumn = pEList->nExpr;
}else{
for(i=0; i<nColumn; i++){
sqliteVdbeAddOp(v, OP_Field, srcTab, i, 0, 0);
}
}
/* 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( 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, nColumn, 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].sortOrder ? '-' : '+';
sqliteExprCode(pParse, pOrderBy->a[i].pExpr);
}
zSortOrder[pOrderBy->nExpr] = 0;
sqliteVdbeAddOp(v, OP_SortMakeKey, pOrderBy->nExpr, 0, zSortOrder, 0);
sqliteFree(zSortOrder);
sqliteVdbeAddOp(v, OP_SortPut, 0, 0, 0, 0);
}else
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
if( eDest==SRT_Union ){
sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0, 0, 0);
sqliteVdbeAddOp(v, OP_String, iParm, 0, "", 0);
sqliteVdbeAddOp(v, OP_Put, iParm, 0, 0, 0);
}else
/* Store the result as data using a unique key.
*/
if( eDest==SRT_Table ){
sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 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
/* 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.
*/
if( eDest==SRT_Except ){
sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Delete, 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( nColumn==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 ){
assert( nColumn==1 );
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, nColumn, 0, 0, 0);
}
return 0;
}
/*
** 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(Vdbe *v, int nColumn){
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, nColumn, 0, 0, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, addr, 0, 0);
sqliteVdbeAddOp(v, OP_SortClose, 0, 0, 0, end);
}
/*
** Generate code that will tell the VDBE how many columns there
** are in the result and the name for each column. This information
** is used to provide "argc" and "azCol[]" values in the callback.
*/
static
void generateColumnNames(Parse *pParse, IdList *pTabList, ExprList *pEList){
Vdbe *v = pParse->pVdbe;
int i;
if( pParse->colNamesSet || v==0 || sqlite_malloc_failed ) return;
pParse->colNamesSet = 1;
sqliteVdbeAddOp(v, OP_ColumnCount, pEList->nExpr, 0, 0, 0);
for(i=0; i<pEList->nExpr; i++){
Expr *p;
int addr;
if( pEList->a[i].zName ){
char *zName = pEList->a[i].zName;
sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
continue;
}
p = pEList->a[i].pExpr;
if( p==0 ) continue;
if( p->span.z && p->span.z[0] ){
addr = sqliteVdbeAddOp(v,OP_ColumnName, i, 0, 0, 0);
sqliteVdbeChangeP3(v, addr, p->span.z, p->span.n);
sqliteVdbeCompressSpace(v, addr);
}else if( p->op!=TK_COLUMN || pTabList==0 ){
char zName[30];
sprintf(zName, "column%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->iColumn].zName, 0);
sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
sqliteFree(zName);
}else{
Table *pTab = pTabList->a[0].pTab;
char *zName = pTab->aCol[p->iColumn].zName;
sqliteVdbeAddOp(v, OP_ColumnName, i, 0, zName, 0);
}
}
}
}
/*
** 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;
}
/*
** For the given SELECT statement, do two things.
**
** (1) Fill in the pTabList->a[].pTab fields in the IdList that
** defines the set of tables that should be scanned.
**
** (2) If the columns to be extracted variable (pEList) is NULL
** (meaning that a "*" was used in the SQL statement) then
** create a fake pEList containing the names of all columns
** of all tables.
**
** Return 0 on success. If there are problems, leave an error message
** in pParse and return non-zero.
*/
static int fillInColumnList(Parse *pParse, Select *p){
int i, j;
IdList *pTabList;
ExprList *pEList;
if( p==0 || p->pSrc==0 ) return 1;
pTabList = p->pSrc;
pEList = p->pEList;
/* Look up every table in the table list.
*/
for(i=0; i<pTabList->nId; i++){
if( pTabList->a[i].pTab ){
/* This routine has run before! No need to continue */
return 0;
}
if( pTabList->a[i].zName==0 ){
/* No table name is given. Instead, there is a (SELECT ...) statement
** the results of which should be used in place of the table. The
** was this is implemented is that the (SELECT ...) writes its results
** into a temporary table which is then scanned like any other table.
*/
sqliteSetString(&pParse->zErrMsg,
"(SELECT...) in a FROM clause is not yet implemented.", 0);
pParse->nErr++;
return 1;
}
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;
}
}
/* If the list of columns to retrieve is "*" then replace it with
** a list of all columns 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_DOT, 0, 0, 0);
if( pExpr==0 ) break;
pExpr->pLeft = sqliteExpr(TK_ID, 0, 0, 0);
if( pExpr->pLeft==0 ) break;
pExpr->pLeft->token.z = pTab->zName;
pExpr->pLeft->token.n = strlen(pTab->zName);
pExpr->pRight = sqliteExpr(TK_ID, 0, 0, 0);
if( pExpr->pRight==0 ) break;
pExpr->pRight->token.z = pTab->aCol[j].zName;
pExpr->pRight->token.n = strlen(pTab->aCol[j].zName);
pExpr->span.z = "";
pExpr->span.n = 0;
pEList = sqliteExprListAppend(pEList, pExpr, 0);
}
}
p->pEList = pEList;
}
return 0;
}
/*
** 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 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( fillInColumnList(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 match = 0;
if( pOrderBy->a[i].done ) continue;
for(j=0; j<pEList->nExpr; j++){
if( pEList->a[j].zName && (pE->op==TK_ID || pE->op==TK_STRING) ){
char *zName = pEList->a[j].zName;
char *zLabel = sqliteStrNDup(pE->token.z, pE->token.n);
sqliteDequote(zLabel);
if( sqliteStrICmp(zName, zLabel)==0 ){
match = 1;
}
sqliteFree(zLabel);
}
if( match==0 && sqliteExprCompare(pE, pEList->a[j].pExpr) ){
match = 1;
}
if( match ){
pE->op = TK_COLUMN;
pE->iColumn = j;
pE->iTable = iTable;
pOrderBy->a[i].done = 1;
break;
}
}
if( !match && mustComplete ){
char zBuf[30];
sprintf(zBuf,"%d",i+1);
sqliteSetString(&pParse->zErrMsg, "ORDER BY term number ", zBuf,
" does not match any result column", 0);
pParse->nErr++;
nErr++;
break;
}
}
return nErr;
}
/*
** 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 *sqliteGetVdbe(Parse *pParse){
Vdbe *v = pParse->pVdbe;
if( v==0 ){
v = pParse->pVdbe = sqliteVdbeCreate(pParse->db);
}
return v;
}
/*
** This routine is called to process a query that is really the union
** or intersection of two or more separate queries.
*/
static int multiSelect(Parse *pParse, Select *p, int eDest, int iParm){
int rc; /* Success code from a subroutine */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
int base; /* Baseline value for pParse->nTab */
/* Make sure there is no ORDER BY clause on prior SELECTs. Only the
** last SELECT in the series may have an ORDER BY.
*/
if( p==0 || p->pPrior==0 ) return 1;
pPrior = p->pPrior;
if( pPrior->pOrderBy ){
sqliteSetString(&pParse->zErrMsg,"ORDER BY clause should come after ",
selectOpName(p->op), " not before", 0);
pParse->nErr++;
return 1;
}
/* Make sure we have a valid query engine. If not, create a new one.
*/
v = sqliteGetVdbe(pParse);
if( v==0 ) return 1;
/* Process the UNION or INTERSECTION
*/
base = pParse->nTab;
switch( p->op ){
case TK_ALL:
case TK_EXCEPT:
case TK_UNION: {
int unionTab; /* Cursor number of the temporary table holding result */
int op; /* One of the SRT_ operations to apply to self */
int priorOp; /* The SRT_ operation to apply to prior selects */
priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
if( eDest==priorOp ){
/* We can reuse a temporary table generated by a SELECT to our
** right. This also means we are not the right-most select and so
** we cannot have an ORDER BY clause
*/
unionTab = iParm;
assert( p->pOrderBy==0 );
}else{
/* We will need to create our own temporary table to hold the
** intermediate results.
*/
unionTab = pParse->nTab++;
if( p->pOrderBy
&& matchOrderbyToColumn(pParse, p, p->pOrderBy, unionTab, 1) ){
return 1;
}
if( p->op!=TK_ALL ){
sqliteVdbeAddOp(v, OP_OpenTemp, unionTab, 0, 0, 0);
sqliteVdbeAddOp(v, OP_KeyAsData, unionTab, 1, 0, 0);
}else{
sqliteVdbeAddOp(v, OP_OpenTemp, unionTab, 0, 0, 0);
}
}
/* Code the SELECT statements to our left
*/
rc = sqliteSelect(pParse, pPrior, priorOp, unionTab);
if( rc ) return rc;
/* 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;
rc = sqliteSelect(pParse, p, op, unionTab);
p->pPrior = pPrior;
if( rc ) return rc;
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
if( eDest!=priorOp ){
int iCont, iBreak;
assert( p->pEList );
generateColumnNames(pParse, 0, p->pEList);
if( p->pOrderBy ){
sqliteVdbeAddOp(v, OP_SortOpen, 0, 0, 0, 0);
}
iBreak = sqliteVdbeMakeLabel(v);
iCont = sqliteVdbeAddOp(v, OP_Next, unionTab, iBreak, 0, 0);
rc = selectInnerLoop(pParse, 0, unionTab, p->pEList->nExpr,
p->pOrderBy, -1, eDest, iParm,
iCont, iBreak);
if( rc ) return 1;
sqliteVdbeAddOp(v, OP_Goto, 0, iCont, 0, 0);
sqliteVdbeAddOp(v, OP_Close, unionTab, 0, 0, iBreak);
if( p->pOrderBy ){
generateSortTail(v, p->pEList->nExpr);
}
}
break;
}
case TK_INTERSECT: {
int tab1, tab2;
int iCont, iBreak;
/* 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( p->pOrderBy && matchOrderbyToColumn(pParse,p,p->pOrderBy,tab1,1) ){
return 1;
}
sqliteVdbeAddOp(v, OP_OpenTemp, tab1, 0, 0, 0);
sqliteVdbeAddOp(v, OP_KeyAsData, tab1, 1, 0, 0);
/* Code the SELECTs to our left into temporary table "tab1".
*/
rc = sqliteSelect(pParse, pPrior, SRT_Union, tab1);
if( rc ) return rc;
/* Code the current SELECT into temporary table "tab2"
*/
sqliteVdbeAddOp(v, OP_OpenTemp, tab2, 0, 0, 0);
sqliteVdbeAddOp(v, OP_KeyAsData, tab2, 1, 0, 0);
p->pPrior = 0;
rc = sqliteSelect(pParse, p, SRT_Union, tab2);
p->pPrior = pPrior;
if( rc ) return rc;
/* Generate code to take the intersection of the two temporary
** tables.
*/
assert( p->pEList );
generateColumnNames(pParse, 0, p->pEList);
if( p->pOrderBy ){
sqliteVdbeAddOp(v, OP_SortOpen, 0, 0, 0, 0);
}
iBreak = sqliteVdbeMakeLabel(v);
iCont = sqliteVdbeAddOp(v, OP_Next, tab1, iBreak, 0, 0);
sqliteVdbeAddOp(v, OP_FullKey, tab1, 0, 0, 0);
sqliteVdbeAddOp(v, OP_NotFound, tab2, iCont, 0, 0);
rc = selectInnerLoop(pParse, 0, tab1, p->pEList->nExpr,
p->pOrderBy, -1, eDest, iParm,
iCont, iBreak);
if( rc ) return 1;
sqliteVdbeAddOp(v, OP_Goto, 0, iCont, 0, 0);
sqliteVdbeAddOp(v, OP_Close, tab2, 0, 0, iBreak);
sqliteVdbeAddOp(v, OP_Close, tab1, 0, 0, 0);
if( p->pOrderBy ){
generateSortTail(v, p->pEList->nExpr);
}
break;
}
}
assert( p->pEList && pPrior->pEList );
if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
sqliteSetString(&pParse->zErrMsg, "SELECTs to the left and right of ",
selectOpName(p->op), " do not have the same number of result columns", 0);
pParse->nErr++;
return 1;
}
pParse->nTab = base;
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_Union Store results as a key in a temporary table iParm
**
** SRT_Except Remove results form the temporary table iParm.
**
** SRT_Table Store results in temporary table 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 Mem Set Union Except */
int iParm /* Save result in this memory location, if >=0 */
){
int i;
WhereInfo *pWInfo;
Vdbe *v;
int isAgg = 0; /* True for select lists like "count(*)" */
ExprList *pEList; /* List of columns 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 */
int base; /* First cursor available for use */
if( sqlite_malloc_failed || pParse->nErr || p==0 ) return 1;
/* If there is are a sequence of queries, do the earlier ones first.
*/
if( p->pPrior ){
return multiSelect(pParse, p, eDest, iParm);
}
/* Make local copies of the parameters for this query.
*/
pTabList = p->pSrc;
pWhere = p->pWhere;
pOrderBy = p->pOrderBy;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
isDistinct = p->isDistinct;
/* Save the current value of pParse->nTab. Restore this value before
** we exit.
*/
base = pParse->nTab;
/*
** Do not even attempt to generate any code if we have already seen
** errors before this routine starts.
*/
if( pParse->nErr>0 ) return 1;
sqliteParseInfoReset(pParse);
/* Look up every table in the table list and create an appropriate
** columnlist in pEList if there isn't one already. (The parser leaves
** a NULL in the p->pEList if the SQL said "SELECT * FROM ...")
*/
if( fillInColumnList(pParse, p) ){
return 1;
}
pEList = p->pEList;
if( pEList==0 ) 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 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);
/* At this point, we should have allocated all the cursors that we
** need to handle subquerys and temporary tables. From here on we
** are committed to keeping the same value for pParse->nTab.
**
** Resolve the column 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 ){
assert( pParse->nAgg==0 && pParse->iAggCount<0 );
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;
}
if( pOrderBy ){
for(i=0; i<pOrderBy->nExpr; i++){
if( sqliteExprAnalyzeAggregates(pParse, pOrderBy->a[i].pExpr) ){
return 1;
}
}
}
}
/* Begin generating code.
*/
v = sqliteGetVdbe(pParse);
if( v==0 ) 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 ){
generateColumnNames(pParse, pTabList, pEList);
}
/* 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_OpenTemp, distinct, 0, 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, 0, 0, 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->iColumn ){
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, 0, 0, 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 ){
generateSortTail(v, pEList->nExpr);
}
pParse->nTab = base;
return 0;
}