/*
** 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 1.63 2002/02/19 22:42:05 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 */
int nLimit, /* LIMIT value. -1 means not used */
int nOffset /* OFFSET value. -1 means not used */
){
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;
pNew->nLimit = nLimit;
pNew->nOffset = nOffset;
}
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.
*/
static void sqliteAggregateInfoReset(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_Column, srcTab, i);
}
}
/* 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);
sqliteVdbeAddOp(v, OP_Distinct, distinct, lbl);
sqliteVdbeAddOp(v, OP_Pop, pEList->nExpr+1, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, iContinue);
sqliteVdbeResolveLabel(v, lbl);
sqliteVdbeAddOp(v, OP_String, 0, 0);
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, 0);
sqliteVdbeAddOp(v, OP_String, iParm, 0);
sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0);
}else
/* Store the result as data using a unique key.
*/
if( eDest==SRT_Table ){
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 = sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0);
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_String, 0, 0);
sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 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, 1);
sqliteVdbeAddOp(v, OP_Goto, 0, iBreak);
}else
/* If none of the above, send the data to the callback function.
*/
{
sqliteVdbeAddOp(v, OP_Callback, nColumn, iBreak);
}
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);
addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end);
sqliteVdbeAddOp(v, OP_SortCallback, nColumn, end);
sqliteVdbeAddOp(v, OP_Goto, 0, addr);
sqliteVdbeResolveLabel(v, end);
sqliteVdbeAddOp(v, OP_SortReset, 0, 0);
}
/*
** 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);
for(i=0; i<pEList->nExpr; i++){
Expr *p;
int showFullNames;
if( pEList->a[i].zName ){
char *zName = pEList->a[i].zName;
sqliteVdbeAddOp(v, OP_ColumnName, i, 0);
sqliteVdbeChangeP3(v, -1, zName, strlen(zName));
continue;
}
p = pEList->a[i].pExpr;
if( p==0 ) continue;
showFullNames = (pParse->db->flags & SQLITE_FullColNames)!=0;
if( p->span.z && p->span.z[0] && !showFullNames ){
int addr = sqliteVdbeAddOp(v,OP_ColumnName, i, 0);
sqliteVdbeChangeP3(v, -1, p->span.z, p->span.n);
sqliteVdbeCompressSpace(v, addr);
}else if( p->op==TK_COLUMN && pTabList ){
Table *pTab = pTabList->a[p->iTable - pParse->nTab].pTab;
char *zCol;
int iCol = p->iColumn;
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
zCol = iCol<0 ? "_ROWID_" : pTab->aCol[iCol].zName;
if( pTabList->nId>1 || showFullNames ){
char *zName = 0;
char *zTab;
zTab = pTabList->a[p->iTable - pParse->nTab].zAlias;
if( showFullNames || zTab==0 ) zTab = pTab->zName;
sqliteSetString(&zName, zTab, ".", zCol, 0);
sqliteVdbeAddOp(v, OP_ColumnName, i, 0);
sqliteVdbeChangeP3(v, -1, zName, strlen(zName));
sqliteFree(zName);
}else{
sqliteVdbeAddOp(v, OP_ColumnName, i, 0);
sqliteVdbeChangeP3(v, -1, zCol, 0);
}
}else if( p->span.z && p->span.z[0] ){
int addr = sqliteVdbeAddOp(v,OP_ColumnName, i, 0);
sqliteVdbeChangeP3(v, -1, p->span.z, p->span.n);
sqliteVdbeCompressSpace(v, addr);
}else{
char zName[30];
assert( p->op!=TK_COLUMN || pTabList==0 );
sprintf(zName, "column%d", i+1);
sqliteVdbeAddOp(v, OP_ColumnName, i, 0);
sqliteVdbeChangeP3(v, -1, zName, strlen(zName));
}
}
}
/*
** 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;
}
/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqliteResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){
Table *pTab;
int i;
ExprList *pEList;
static int fillInColumnList(Parse*, Select*);
if( fillInColumnList(pParse, pSelect) ){
return 0;
}
pTab = sqliteMalloc( sizeof(Table) );
if( pTab==0 ){
return 0;
}
pTab->zName = zTabName ? sqliteStrDup(zTabName) : 0;
pEList = pSelect->pEList;
pTab->nCol = pEList->nExpr;
pTab->aCol = sqliteMalloc( sizeof(pTab->aCol[0])*pTab->nCol );
for(i=0; i<pTab->nCol; i++){
Expr *p;
if( pEList->a[i].zName ){
pTab->aCol[i].zName = sqliteStrDup(pEList->a[i].zName);
}else if( (p=pEList->a[i].pExpr)->span.z && p->span.z[0] ){
sqliteSetNString(&pTab->aCol[i].zName, p->span.z, p->span.n, 0);
}else if( p->op==TK_DOT && p->pRight && p->pRight->token.z &&
p->pRight->token.z[0] ){
sqliteSetNString(&pTab->aCol[i].zName,
p->pRight->token.z, p->pRight->token.n, 0);
}else{
char zBuf[30];
sprintf(zBuf, "column%d", i+1);
pTab->aCol[i].zName = sqliteStrDup(zBuf);
}
}
pTab->iPKey = -1;
return pTab;
}
/*
** 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, k;
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 ){
/* A sub-query in the FROM clause of a SELECT */
Table *pTab;
assert( pTabList->a[i].pSelect!=0 );
pTabList->a[i].pTab = pTab =
sqliteResultSetOfSelect(pParse, pTabList->a[i].zAlias,
pTabList->a[i].pSelect);
if( pTab==0 ){
return 1;
}
pTab->isTransient = 1;
}else{
/* An ordinary table name in the FROM clause */
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;
}
}
}
/* For every "*" that occurs in the column list, insert the names of
** all columns in all tables. 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.
*/
for(k=0; k<pEList->nExpr; k++){
if( pEList->a[k].pExpr->op==TK_ALL ) break;
}
if( k<pEList->nExpr ){
struct ExprList_item *a = pEList->a;
ExprList *pNew = 0;
for(k=0; k<pEList->nExpr; k++){
if( a[k].pExpr->op!=TK_ALL ){
pNew = sqliteExprListAppend(pNew, a[k].pExpr, 0);
pNew->a[pNew->nExpr-1].zName = a[k].zName;
a[k].pExpr = 0;
a[k].zName = 0;
}else{
for(i=0; i<pTabList->nId; i++){
Table *pTab = pTabList->a[i].pTab;
for(j=0; j<pTab->nCol; j++){
Expr *pExpr, *pLeft, *pRight;
pRight = sqliteExpr(TK_ID, 0, 0, 0);
if( pRight==0 ) break;
pRight->token.z = pTab->aCol[j].zName;
pRight->token.n = strlen(pTab->aCol[j].zName);
if( pTab->zName ){
pLeft = sqliteExpr(TK_ID, 0, 0, 0);
if( pLeft==0 ) break;
if( pTabList->a[i].zAlias && pTabList->a[i].zAlias[0] ){
pLeft->token.z = pTabList->a[i].zAlias;
pLeft->token.n = strlen(pTabList->a[i].zAlias);
}else{
pLeft->token.z = pTab->zName;
pLeft->token.n = strlen(pTab->zName);
}
pExpr = sqliteExpr(TK_DOT, pLeft, pRight, 0);
if( pExpr==0 ) break;
}else{
pExpr = pRight;
pExpr->span = pExpr->token;
}
pNew = sqliteExprListAppend(pNew, pExpr, 0);
}
}
}
}
sqliteExprListDelete(pEList);
p->pEList = pNew;
}
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, 1);
sqliteVdbeAddOp(v, OP_KeyAsData, unionTab, 1);
}else{
sqliteVdbeAddOp(v, OP_OpenTemp, unionTab, 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, iStart;
assert( p->pEList );
generateColumnNames(pParse, 0, p->pEList);
iBreak = sqliteVdbeMakeLabel(v);
iCont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_Rewind, unionTab, iBreak);
iStart = sqliteVdbeCurrentAddr(v);
rc = selectInnerLoop(pParse, 0, unionTab, p->pEList->nExpr,
p->pOrderBy, -1, eDest, iParm,
iCont, iBreak);
if( rc ) return 1;
sqliteVdbeResolveLabel(v, iCont);
sqliteVdbeAddOp(v, OP_Next, unionTab, iStart);
sqliteVdbeResolveLabel(v, iBreak);
sqliteVdbeAddOp(v, OP_Close, unionTab, 0);
if( p->pOrderBy ){
generateSortTail(v, p->pEList->nExpr);
}
}
break;
}
case TK_INTERSECT: {
int tab1, tab2;
int iCont, iBreak, iStart;
/* 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, 1);
sqliteVdbeAddOp(v, OP_KeyAsData, tab1, 1);
/* 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, 1);
sqliteVdbeAddOp(v, OP_KeyAsData, tab2, 1);
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);
iBreak = sqliteVdbeMakeLabel(v);
iCont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_Rewind, tab1, iBreak);
iStart = sqliteVdbeAddOp(v, OP_FullKey, tab1, 0);
sqliteVdbeAddOp(v, OP_NotFound, tab2, iCont);
rc = selectInnerLoop(pParse, 0, tab1, p->pEList->nExpr,
p->pOrderBy, -1, eDest, iParm,
iCont, iBreak);
if( rc ) return 1;
sqliteVdbeResolveLabel(v, iCont);
sqliteVdbeAddOp(v, OP_Next, tab1, iStart);
sqliteVdbeResolveLabel(v, iBreak);
sqliteVdbeAddOp(v, OP_Close, tab2, 0);
sqliteVdbeAddOp(v, OP_Close, tab1, 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;
}
/*
** 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 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 sqliteSelect().
** 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 openOp;
int seekOp;
int cont;
ExprList eList;
struct ExprList_item eListItem;
/* 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;
if( p->pSrc->nId!=1 ) return 0;
if( p->pEList->nExpr!=1 ) return 0;
pExpr = p->pEList->a[0].pExpr;
if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
if( pExpr->pList==0 || pExpr->pList->nExpr!=1 ) return 0;
if( pExpr->iColumn!=FN_Min && pExpr->iColumn!=FN_Max ) return 0;
seekOp = pExpr->iColumn==FN_Min ? OP_Rewind : OP_Last;
pExpr = pExpr->pList->a[0].pExpr;
if( pExpr->op!=TK_COLUMN ) return 0;
iCol = pExpr->iColumn;
pTab = p->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.
*/
if( iCol<0 ){
pIdx = 0;
}else{
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
assert( pIdx->nColumn>=1 );
if( pIdx->aiColumn[0]==iCol ) break;
}
if( pIdx==0 ) return 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.
*/
v = sqliteGetVdbe(pParse);
if( v==0 ) return 0;
if( eDest==SRT_Callback ){
generateColumnNames(pParse, p->pSrc, p->pEList);
}
/* Begin generating code
*/
if( !pParse->schemaVerified && (pParse->db->flags & SQLITE_InTrans)==0 ){
sqliteVdbeAddOp(v, OP_VerifyCookie, pParse->db->schema_cookie, 0);
pParse->schemaVerified = 1;
}
openOp = pTab->isTemp ? OP_OpenAux : OP_Open;
base = pParse->nTab;
sqliteVdbeAddOp(v, openOp, base, pTab->tnum);
sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
if( pIdx==0 ){
sqliteVdbeAddOp(v, seekOp, base, 0);
}else{
sqliteVdbeAddOp(v, openOp, base+1, pIdx->tnum);
sqliteVdbeChangeP3(v, -1, pIdx->zName, P3_STATIC);
sqliteVdbeAddOp(v, seekOp, base+1, 0);
sqliteVdbeAddOp(v, OP_IdxRecno, base+1, 0);
sqliteVdbeAddOp(v, OP_Close, base+1, 0);
sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
}
eList.nExpr = 1;
memset(&eListItem, 0, sizeof(eListItem));
eList.a = &eListItem;
eList.a[0].pExpr = pExpr;
cont = sqliteVdbeMakeLabel(v);
selectInnerLoop(pParse, &eList, base, 1, 0, -1, eDest, iParm, cont, cont);
sqliteVdbeResolveLabel(v, cont);
sqliteVdbeAddOp(v, OP_Close, base, 0);
return 1;
}
/*
** 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. */
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 */
int rc = 1; /* Value to return from this function */
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 ) goto select_end;
/* 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) ){
goto select_end;
}
pEList = p->pEList;
if( pEList==0 ) goto select_end;
/* 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++;
goto select_end;
}
/* 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, 0, pEList->a[i].pExpr) ){
goto select_end;
}
if( sqliteExprCheck(pParse, pEList->a[i].pExpr, 1, &isAgg) ){
goto select_end;
}
}
if( pWhere ){
if( sqliteExprResolveIds(pParse, pTabList, pEList, pWhere) ){
goto select_end;
}
if( sqliteExprCheck(pParse, pWhere, 0, 0) ){
goto select_end;
}
}
if( pOrderBy ){
for(i=0; i<pOrderBy->nExpr; i++){
Expr *pE = pOrderBy->a[i].pExpr;
if( sqliteExprIsConstant(pE) ){
sqliteSetString(&pParse->zErrMsg,
"ORDER BY expressions should not be constant", 0);
pParse->nErr++;
goto select_end;
}
if( sqliteExprResolveIds(pParse, pTabList, pEList, pE) ){
goto select_end;
}
if( sqliteExprCheck(pParse, pE, isAgg, 0) ){
goto select_end;
}
}
}
if( pGroupBy ){
for(i=0; i<pGroupBy->nExpr; i++){
Expr *pE = pGroupBy->a[i].pExpr;
if( sqliteExprIsConstant(pE) ){
sqliteSetString(&pParse->zErrMsg,
"GROUP BY expressions should not be constant", 0);
pParse->nErr++;
goto select_end;
}
if( sqliteExprResolveIds(pParse, pTabList, pEList, pE) ){
goto select_end;
}
if( sqliteExprCheck(pParse, pE, isAgg, 0) ){
goto select_end;
}
}
}
if( pHaving ){
if( pGroupBy==0 ){
sqliteSetString(&pParse->zErrMsg, "a GROUP BY clause is required "
"before HAVING", 0);
pParse->nErr++;
goto select_end;
}
if( sqliteExprResolveIds(pParse, pTabList, pEList, pHaving) ){
goto select_end;
}
if( sqliteExprCheck(pParse, pHaving, isAgg, 0) ){
goto select_end;
}
}
/* 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;
}
/* Begin generating code.
*/
v = sqliteGetVdbe(pParse);
if( v==0 ) goto select_end;
/* Generate code for all sub-queries in the FROM clause
*/
for(i=0; i<pTabList->nId; i++){
int oldNTab;
Table *pTab = pTabList->a[i].pTab;
if( !pTab->isTransient ) continue;
assert( pTabList->a[i].pSelect!=0 );
oldNTab = pParse->nTab;
pParse->nTab += i+1;
sqliteVdbeAddOp(v, OP_OpenTemp, oldNTab+i, 0);
sqliteSelect(pParse, pTabList->a[i].pSelect, SRT_Table, oldNTab+i);
pParse->nTab = oldNTab;
}
/* Do an analysis of aggregate expressions.
*/
sqliteAggregateInfoReset(pParse);
if( isAgg ){
assert( pParse->nAgg==0 && pParse->iAggCount<0 );
for(i=0; i<pEList->nExpr; i++){
if( sqliteExprAnalyzeAggregates(pParse, pEList->a[i].pExpr) ){
goto select_end;
}
}
if( pGroupBy ){
for(i=0; i<pGroupBy->nExpr; i++){
if( sqliteExprAnalyzeAggregates(pParse, pGroupBy->a[i].pExpr) ){
goto select_end;
}
}
}
if( pHaving && sqliteExprAnalyzeAggregates(pParse, pHaving) ){
goto select_end;
}
if( pOrderBy ){
for(i=0; i<pOrderBy->nExpr; i++){
if( sqliteExprAnalyzeAggregates(pParse, pOrderBy->a[i].pExpr) ){
goto select_end;
}
}
}
}
/* Set the limiter
*/
if( p->nLimit<=0 ){
p->nOffset = 0;
}else{
if( p->nOffset<0 ) p->nOffset = 0;
sqliteVdbeAddOp(v, OP_Limit, p->nLimit, p->nOffset);
}
/* 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);
if( pGroupBy==0 ){
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_AggFocus, 0, 0);
for(i=0; i<pParse->nAgg; i++){
Expr *pE;
if( !pParse->aAgg[i].isAgg ) continue;
pE = pParse->aAgg[i].pExpr;
assert( pE==0 || pE->op==TK_AGG_FUNCTION );
assert( pE==0 || (pE->pList!=0 && pE->pList->nExpr==1) );
if( pE==0 || pE->iColumn==FN_Sum ){
sqliteVdbeAddOp(v, OP_Integer, 0, 0);
sqliteVdbeAddOp(v, OP_AggSet, 0, i);
continue;
}
}
}
}
/* Initialize the memory cell to NULL
*/
if( eDest==SRT_Mem ){
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, iParm, 1);
}
/* Begin the database scan
*/
if( isDistinct ){
sqliteVdbeAddOp(v, OP_OpenTemp, distinct, 1);
}
pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 0);
if( pWInfo==0 ) goto select_end;
/* 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) ){
goto select_end;
}
}
/* If we are dealing with aggregates, then to the special aggregate
** processing.
*/
else{
if( pGroupBy ){
int lbl1;
for(i=0; i<pGroupBy->nExpr; i++){
sqliteExprCode(pParse, pGroupBy->a[i].pExpr);
}
sqliteVdbeAddOp(v, OP_MakeKey, pGroupBy->nExpr, 0);
lbl1 = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_AggFocus, 0, lbl1);
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);
}
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);
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);
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);
sqliteVdbeAddOp(v, OP_AggSet, 0, i);
}
}
/* 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);
pParse->useAgg = 1;
if( pHaving ){
sqliteExprIfFalse(pParse, pHaving, startagg);
}
if( selectInnerLoop(pParse, pEList, 0, 0, pOrderBy, distinct, eDest, iParm,
startagg, endagg) ){
goto select_end;
}
sqliteVdbeAddOp(v, OP_Goto, 0, startagg);
sqliteVdbeResolveLabel(v, endagg);
sqliteVdbeAddOp(v, OP_Noop, 0, 0);
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;
/* Issue a null callback if that is what the user wants.
*/
if( (pParse->db->flags & SQLITE_NullCallback)!=0 && eDest==SRT_Callback ){
sqliteVdbeAddOp(v, OP_NullCallback, pEList->nExpr, 0);
}
/* 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:
sqliteAggregateInfoReset(pParse);
return rc;
}