** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
-** $Id: select.c,v 1.94 2002/06/19 14:27:05 drh Exp $
+** $Id: select.c,v 1.95 2002/06/20 03:38:26 drh Exp $
*/
#include "sqliteInt.h"
pParse->useAgg = 0;
}
+/*
+** Insert code into "v" that will push the record on the top of the
+** stack into the sorter.
+*/
+static void pushOntoSorter(Parse *pParse, Vdbe *v, ExprList *pOrderBy){
+ char *zSortOrder;
+ int i;
+ zSortOrder = sqliteMalloc( pOrderBy->nExpr + 1 );
+ if( zSortOrder==0 ) return;
+ 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);
+ sqliteVdbeChangeP3(v, -1, zSortOrder, strlen(zSortOrder));
+ sqliteFree(zSortOrder);
+ sqliteVdbeAddOp(v, OP_SortPut, 0, 0);
+}
+
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
sqliteVdbeAddOp(v, OP_PutStrKey, distinct, 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);
- 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);
- sqliteVdbeChangeP3(v, -1, zSortOrder, strlen(zSortOrder));
- sqliteFree(zSortOrder);
- sqliteVdbeAddOp(v, OP_SortPut, 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, NULL_ALWAYS_DISTINCT);
- sqliteVdbeAddOp(v, OP_String, 0, 0);
- sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0);
- }else
+ switch( eDest ){
+ /* In this mode, write each query result to the key of the temporary
+ ** table iParm.
+ */
+ case SRT_Union: {
+ sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, NULL_ALWAYS_DISTINCT);
+ sqliteVdbeAddOp(v, OP_String, 0, 0);
+ sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0);
+ break;
+ }
- /* Store the result as data using a unique key.
- */
- if( eDest==SRT_Table || eDest==SRT_TempTable ){
- sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
- sqliteVdbeAddOp(v, OP_NewRecno, iParm, 0);
- sqliteVdbeAddOp(v, OP_Pull, 1, 0);
- sqliteVdbeAddOp(v, OP_PutIntKey, iParm, 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 ){
- int addr;
- addr = sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, NULL_ALWAYS_DISTINCT);
- sqliteVdbeAddOp(v, OP_NotFound, iParm, addr+3);
- sqliteVdbeAddOp(v, OP_Delete, iParm, 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_IsNull, -1, sqliteVdbeCurrentAddr(v)+3);
- sqliteVdbeAddOp(v, OP_String, 0, 0);
- sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0);
- }else
+ /* Store the result as data using a unique key.
+ */
+ case SRT_Table:
+ case SRT_TempTable: {
+ sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
+ if( pOrderBy ){
+ pushOntoSorter(pParse, v, pOrderBy);
+ }else{
+ sqliteVdbeAddOp(v, OP_NewRecno, iParm, 0);
+ sqliteVdbeAddOp(v, OP_Pull, 1, 0);
+ sqliteVdbeAddOp(v, OP_PutIntKey, 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 = sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, NULL_ALWAYS_DISTINCT);
+ sqliteVdbeAddOp(v, OP_NotFound, iParm, addr+3);
+ sqliteVdbeAddOp(v, OP_Delete, iParm, 0);
+ 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.
- */
- if( eDest==SRT_Mem ){
- assert( nColumn==1 );
- sqliteVdbeAddOp(v, OP_MemStore, iParm, 1);
- sqliteVdbeAddOp(v, OP_Goto, 0, iBreak);
- }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.
+ */
+ case SRT_Set: {
+ assert( nColumn==1 );
+ sqliteVdbeAddOp(v, OP_IsNull, -1, sqliteVdbeCurrentAddr(v)+3);
+ sqliteVdbeAddOp(v, OP_String, 0, 0);
+ if( pOrderBy ){
+ pushOntoSorter(pParse, v, pOrderBy);
+ }else{
+ sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0);
+ }
+ break;
+ }
- /* 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.
- */
- if( eDest==SRT_Discard ){
- sqliteVdbeAddOp(v, OP_Pop, nColumn, 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.
+ */
+ case SRT_Mem: {
+ assert( nColumn==1 );
+ if( pOrderBy ){
+ pushOntoSorter(pParse, v, pOrderBy);
+ }else{
+ sqliteVdbeAddOp(v, OP_MemStore, iParm, 1);
+ sqliteVdbeAddOp(v, OP_Goto, 0, iBreak);
+ }
+ break;
+ }
- /* If none of the above, send the data to the callback function.
- */
- {
- assert( eDest==SRT_Callback );
- sqliteVdbeAddOp(v, OP_Callback, nColumn, 0);
+ /* 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.
+ */
+ case SRT_Discard: {
+ sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
+ break;
+ }
+
+ /* Send the data to the callback function.
+ */
+ default: {
+ assert( eDest==SRT_Callback );
+ if( pOrderBy ){
+ sqliteVdbeAddOp(v, OP_SortMakeRec, nColumn, 0);
+ pushOntoSorter(pParse, v, pOrderBy);
+ }else{
+ sqliteVdbeAddOp(v, OP_Callback, nColumn, 0);
+ }
+ break;
+ }
}
return 0;
}
** we need to run the sorter and output the results. The following
** routine generates the code needed to do that.
*/
-static void generateSortTail(Select *p, Vdbe *v, int nColumn){
+static void generateSortTail(
+ 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 end = sqliteVdbeMakeLabel(v);
int addr;
sqliteVdbeAddOp(v, OP_Sort, 0, 0);
if( p->nLimit>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 0, end);
}
- sqliteVdbeAddOp(v, OP_SortCallback, nColumn, 0);
+ switch( eDest ){
+ case SRT_Callback: {
+ sqliteVdbeAddOp(v, OP_SortCallback, nColumn, 0);
+ break;
+ }
+ case SRT_Table:
+ case SRT_TempTable: {
+ sqliteVdbeAddOp(v, OP_NewRecno, iParm, 0);
+ sqliteVdbeAddOp(v, OP_Pull, 1, 0);
+ sqliteVdbeAddOp(v, OP_PutIntKey, iParm, 0);
+ break;
+ }
+ case SRT_Set: {
+ assert( nColumn==1 );
+ sqliteVdbeAddOp(v, OP_IsNull, -1, sqliteVdbeCurrentAddr(v)+3);
+ sqliteVdbeAddOp(v, OP_String, 0, 0);
+ sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0);
+ break;
+ }
+ case SRT_Mem: {
+ assert( nColumn==1 );
+ sqliteVdbeAddOp(v, OP_MemStore, iParm, 1);
+ sqliteVdbeAddOp(v, OP_Goto, 0, end);
+ break;
+ }
+ default: {
+ assert( end==0 ); /* Cannot happen */
+ break;
+ }
+ }
sqliteVdbeAddOp(v, OP_Goto, 0, addr);
sqliteVdbeResolveLabel(v, end);
sqliteVdbeAddOp(v, OP_SortReset, 0, 0);
/*
** 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 results should
+** be stored in eDest with parameter iParm.
*/
static int multiSelect(Parse *pParse, Select *p, int eDest, int iParm){
int rc; /* Success code from a subroutine */
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 */
+ ExprList *pOrderBy; /* The ORDER BY clause for the right SELECT */
priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
- if( eDest==priorOp ){
+ if( eDest==priorOp && p->pOrderBy==0 ){
/* 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
+ ** right.
*/
unionTab = iParm;
- assert( p->pOrderBy==0 );
}else{
/* We will need to create our own temporary table to hold the
** intermediate results.
case TK_ALL: op = SRT_Table; break;
}
p->pPrior = 0;
+ pOrderBy = p->pOrderBy;
+ p->pOrderBy = 0;
rc = sqliteSelect(pParse, p, op, unionTab, 0, 0, 0);
p->pPrior = pPrior;
+ p->pOrderBy = pOrderBy;
if( rc ) return rc;
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
- if( eDest!=priorOp ){
+ if( eDest!=priorOp || unionTab!=iParm ){
int iCont, iBreak, iStart;
assert( p->pEList );
if( eDest==SRT_Callback ){
sqliteVdbeResolveLabel(v, iBreak);
sqliteVdbeAddOp(v, OP_Close, unionTab, 0);
if( p->pOrderBy ){
- generateSortTail(p, v, p->pEList->nExpr);
+ generateSortTail(p, v, p->pEList->nExpr, eDest, iParm);
}
}
break;
sqliteVdbeAddOp(v, OP_Close, tab2, 0);
sqliteVdbeAddOp(v, OP_Close, tab1, 0);
if( p->pOrderBy ){
- generateSortTail(p, v, p->pEList->nExpr);
+ generateSortTail(p, v, p->pEList->nExpr, eDest, iParm);
}
break;
}
goto select_end;
}
- /* ORDER BY is ignored if we are not sending the result to a callback.
+ /* ORDER BY is ignored for some destinations.
*/
- if( eDest!=SRT_Callback ){
- pOrderBy = 0;
+ switch( eDest ){
+ case SRT_Union:
+ case SRT_Except:
+ case SRT_Discard:
+ pOrderBy = 0;
+ break;
+ default:
+ break;
}
/* At this point, we should have allocated all the cursors that we
** and send them to the callback one by one.
*/
if( pOrderBy ){
- generateSortTail(p, v, pEList->nExpr);
+ generateSortTail(p, v, pEList->nExpr, eDest, iParm);
}
projects / thirdparty / sqlite.git / commitdiff
