/*
** 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 1.98 2002/06/24 12:20:23 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 */
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 */
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);
sqliteSrcListDelete(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;
}
/*
** 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_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 sqliteJoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
int jointype = 0;
Token *apAll[3];
Token *p;
static struct {
const char *zKeyword;
int nChar;
int 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 },
};
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
&& sqliteStrNICmp(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
){
static Token dummy = { 0, 0 };
char *zSp1 = " ", *zSp2 = " ";
if( pB==0 ){ pB = &dummy; zSp1 = 0; }
if( pC==0 ){ pC = &dummy; zSp2 = 0; }
sqliteSetNString(&pParse->zErrMsg, "unknown or unsupported join type: ", 0,
pA->z, pA->n, zSp1, 1, pB->z, pB->n, zSp2, 1, pC->z, pC->n, 0);
pParse->nErr++;
jointype = JT_INNER;
}else if( jointype & JT_RIGHT ){
sqliteSetString(&pParse->zErrMsg,
"RIGHT and FULL OUTER JOINs are not currently supported", 0);
pParse->nErr++;
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( sqliteStrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
}
return -1;
}
/*
** 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 Table *pTab2, /* Second table */
Expr **ppExpr /* Add the equality term to this expression */
){
Token dummy;
Expr *pE1a, *pE1b, *pE1c;
Expr *pE2a, *pE2b, *pE2c;
Expr *pE;
dummy.z = zCol;
dummy.n = strlen(zCol);
pE1a = sqliteExpr(TK_ID, 0, 0, &dummy);
pE2a = sqliteExpr(TK_ID, 0, 0, &dummy);
dummy.z = pTab1->zName;
dummy.n = strlen(dummy.z);
pE1b = sqliteExpr(TK_ID, 0, 0, &dummy);
dummy.z = pTab2->zName;
dummy.n = strlen(dummy.z);
pE2b = sqliteExpr(TK_ID, 0, 0, &dummy);
pE1c = sqliteExpr(TK_DOT, pE1b, pE1a, 0);
pE2c = sqliteExpr(TK_DOT, pE2b, pE2a, 0);
pE = sqliteExpr(TK_EQ, pE1c, pE2c, 0);
if( *ppExpr ){
*ppExpr = sqliteExpr(TK_AND, *ppExpr, pE, 0);
}else{
*ppExpr = pE;
}
}
/*
** 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.
**
** This routine returns the number of errors encountered.
*/
static int sqliteProcessJoin(Parse *pParse, Select *p){
SrcList *pSrc;
int i, j;
pSrc = p->pSrc;
for(i=0; i<pSrc->nSrc-1; i++){
struct SrcList_item *pTerm = &pSrc->a[i];
struct SrcList_item *pOther = &pSrc->a[i+1];
if( pTerm->pTab==0 || pOther->pTab==0 ) continue;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if( pTerm->jointype & JT_NATURAL ){
Table *pTab;
if( pTerm->pOn || pTerm->pUsing ){
sqliteSetString(&pParse->zErrMsg, "a NATURAL join may not have "
"an ON or USING clause", 0);
pParse->nErr++;
return 1;
}
pTab = pTerm->pTab;
for(j=0; j<pTab->nCol; j++){
if( columnIndex(pOther->pTab, pTab->aCol[j].zName)>=0 ){
addWhereTerm(pTab->aCol[j].zName, pTab, pOther->pTab, &p->pWhere);
}
}
}
/* Disallow both ON and USING clauses in the same join
*/
if( pTerm->pOn && pTerm->pUsing ){
sqliteSetString(&pParse->zErrMsg, "cannot have both ON and USING "
"clauses in the same join", 0);
pParse->nErr++;
return 1;
}
/* Add the ON clause to the end of the WHERE clause, connected by
** and AND operator.
*/
if( pTerm->pOn ){
if( p->pWhere==0 ){
p->pWhere = pTerm->pOn;
}else{
p->pWhere = sqliteExpr(TK_AND, p->pWhere, pTerm->pOn, 0);
}
pTerm->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( pTerm->pUsing ){
IdList *pList;
int j;
assert( i<pSrc->nSrc-1 );
pList = pTerm->pUsing;
for(j=0; j<pList->nId; j++){
if( columnIndex(pTerm->pTab, pList->a[j].zName)<0 ||
columnIndex(pOther->pTab, pList->a[j].zName)<0 ){
sqliteSetString(&pParse->zErrMsg, "cannot join using column ",
pList->a[j].zName, " - column not present in both tables", 0);
pParse->nErr++;
return 1;
}
addWhereTerm(pList->a[j].zName, pTerm->pTab, pOther->pTab, &p->pWhere);
}
}
}
return 0;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqliteSelectDelete(Select *p){
if( p==0 ) return;
sqliteExprListDelete(p->pEList);
sqliteSrcListDelete(p->pSrc);
sqliteExprDelete(p->pWhere);
sqliteExprListDelete(p->pGroupBy);
sqliteExprDelete(p->pHaving);
sqliteExprListDelete(p->pOrderBy);
sqliteSelectDelete(p->pPrior);
sqliteFree(p->zSelect);
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->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.
**
** 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 */
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 */
){
Vdbe *v = pParse->pVdbe;
int i;
if( v==0 ) return 0;
/* If there was a LIMIT clause on the SELECT statement, then do the check
** to see if this row should be output.
*/
if( pOrderBy==0 ){
if( p->nOffset>0 ){
int addr = sqliteVdbeCurrentAddr(v);
sqliteVdbeAddOp(v, OP_MemIncr, p->nOffset, addr+2);
sqliteVdbeAddOp(v, OP_Goto, 0, iContinue);
}
if( p->nLimit>=0 ){
sqliteVdbeAddOp(v, OP_MemIncr, p->nLimit, iBreak);
}
}
/* 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 && pEList && pEList->nExpr>0 ){
#if NULL_ALWAYS_DISTINCT
sqliteVdbeAddOp(v, OP_IsNull, -pEList->nExpr, sqliteVdbeCurrentAddr(v)+7);
#endif
sqliteVdbeAddOp(v, OP_MakeKey, pEList->nExpr, 1);
sqliteVdbeAddOp(v, OP_Distinct, distinct, sqliteVdbeCurrentAddr(v)+3);
sqliteVdbeAddOp(v, OP_Pop, pEList->nExpr+1, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, iContinue);
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_PutStrKey, distinct, 0);
}
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.
*/
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 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;
}
/* 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;
}
/* Send the data to the callback function.
*/
case SRT_Callback:
case SRT_Sorter: {
if( pOrderBy ){
sqliteVdbeAddOp(v, OP_SortMakeRec, nColumn, 0);
pushOntoSorter(pParse, v, pOrderBy);
}else{
assert( eDest==SRT_Callback );
sqliteVdbeAddOp(v, OP_Callback, nColumn, 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.
*/
default: {
assert( eDest==SRT_Discard );
sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
break;
}
}
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(
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;
if( eDest==SRT_Sorter ) return;
sqliteVdbeAddOp(v, OP_Sort, 0, 0);
addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end);
if( p->nOffset>0 ){
sqliteVdbeAddOp(v, OP_MemIncr, p->nOffset, addr+4);
sqliteVdbeAddOp(v, OP_Pop, 1, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, addr);
}
if( p->nLimit>=0 ){
sqliteVdbeAddOp(v, OP_MemIncr, p->nLimit, end);
}
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: {
/* Do nothing */
break;
}
}
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, /* Parser context */
int base, /* VDBE cursor corresponding to first entry in pTabList */
SrcList *pTabList, /* List of tables */
ExprList *pEList /* Expressions defining the result set */
){
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 - base].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->nSrc>1 || showFullNames ){
char *zName = 0;
char *zTab;
zTab = pTabList->a[p->iTable - base].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;
assert( pTab->nCol>0 );
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 three things.
**
** (1) Fill in the pTabList->a[].pTab fields in the SrcList that
** defines the set of tables that should be scanned.
**
** (2) Add terms to the WHERE clause to accomodate the NATURAL keyword
** on joins and the ON and USING clause of joins.
**
** (3) 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 fillInColumnList(Parse *pParse, Select *p){
int i, j, k, rc;
SrcList *pTabList;
ExprList *pEList;
Table *pTab;
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->nSrc; 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 */
assert( pTabList->a[i].pSelect!=0 );
if( pTabList->a[i].zAlias==0 ){
char zFakeName[60];
sprintf(zFakeName, "sqlite_subquery_%p_",
(void*)pTabList->a[i].pSelect);
sqliteSetString(&pTabList->a[i].zAlias, zFakeName, 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 or view name in the FROM clause */
pTabList->a[i].pTab = pTab =
sqliteFindTable(pParse->db, pTabList->a[i].zName);
if( pTab==0 ){
sqliteSetString(&pParse->zErrMsg, "no such table: ",
pTabList->a[i].zName, 0);
pParse->nErr++;
return 1;
}
if( pTab->pSelect ){
if( sqliteViewGetColumnNames(pParse, pTab) ){
return 1;
}
pTabList->a[i].pSelect = sqliteSelectDup(pTab->pSelect);
}
}
}
/* 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;
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 = sqliteExprListAppend(pNew, a[k].pExpr, 0);
pNew->a[pNew->nExpr-1].zName = a[k].zName;
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 */
Token *pName; /* text of name of TABLE */
if( pE->op==TK_DOT && pE->pLeft ){
pName = &pE->pLeft->token;
}else{
pName = 0;
}
for(i=0; i<pTabList->nSrc; i++){
Table *pTab = pTabList->a[i].pTab;
char *zTabName = pTabList->a[i].zAlias;
if( zTabName==0 || zTabName[0]==0 ){
zTabName = pTab->zName;
}
if( pName && (zTabName==0 || zTabName[0]==0 ||
sqliteStrNICmp(pName->z, zTabName, pName->n)!=0 ||
zTabName[pName->n]!=0) ){
continue;
}
tableSeen = 1;
for(j=0; j<pTab->nCol; j++){
Expr *pExpr, *pLeft, *pRight;
char *zName = pTab->aCol[j].zName;
if( i>0 && (pTabList->a[i-1].jointype & JT_NATURAL)!=0 &&
columnIndex(pTabList->a[i-1].pTab, zName)>=0 ){
/* In a NATURAL join, omit the join columns from the
** table on the right */
continue;
}
if( i>0 && sqliteIdListIndex(pTabList->a[i-1].pUsing, zName)>=0 ){
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;
}
pRight = sqliteExpr(TK_ID, 0, 0, 0);
if( pRight==0 ) break;
pRight->token.z = zName;
pRight->token.n = strlen(zName);
if( zTabName ){
pLeft = sqliteExpr(TK_ID, 0, 0, 0);
if( pLeft==0 ) break;
pLeft->token.z = zTabName;
pLeft->token.n = strlen(zTabName);
pExpr = sqliteExpr(TK_DOT, pLeft, pRight, 0);
if( pExpr==0 ) break;
}else{
pExpr = pRight;
pExpr->span = pExpr->token;
}
pNew = sqliteExprListAppend(pNew, pExpr, 0);
}
}
if( !tableSeen ){
if( pName ){
sqliteSetNString(&pParse->zErrMsg, "no such table: ", -1,
pName->z, pName->n, 0);
}else{
sqliteSetString(&pParse->zErrMsg, "no tables specified", 0);
}
rc = 1;
}
}
}
sqliteExprListDelete(pEList);
p->pEList = pNew;
}
return rc;
}
/*
** This routine recursively unlinks the Select.pSrc.a[].pTab pointers
** in a select structure. It just sets the pointers to NULL. This
** routine is recursive in the sense that if the Select.pSrc.a[].pSelect
** pointer is not NULL, this routine is called recursively on that pointer.
**
** This routine is called on the Select structure that defines a
** VIEW in order to undo any bindings to tables. This is necessary
** because those tables might be DROPed by a subsequent SQL command.
*/
void sqliteSelectUnbind(Select *p){
int i;
SrcList *pSrc = p->pSrc;
Table *pTab;
if( p==0 ) return;
for(i=0; i<pSrc->nSrc; i++){
if( (pTab = pSrc->a[i].pTab)!=0 ){
if( pTab->isTransient ){
sqliteDeleteTable(0, pTab);
sqliteSelectDelete(pSrc->a[i].pSelect);
pSrc->a[i].pSelect = 0;
}
pSrc->a[i].pTab = 0;
if( pSrc->a[i].pSelect ){
sqliteSelectUnbind(pSrc->a[i].pSelect);
}
}
}
}
/*
** 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( 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 iCol = -1;
if( pOrderBy->a[i].done ) continue;
if( sqliteExprIsInteger(pE, &iCol) ){
if( iCol<=0 || iCol>pEList->nExpr ){
char zBuf[200];
sprintf(zBuf,"ORDER BY position %d should be between 1 and %d",
iCol, pEList->nExpr);
sqliteSetString(&pParse->zErrMsg, zBuf, 0);
pParse->nErr++;
nErr++;
break;
}
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;
assert( pE->token.z );
zLabel = sqliteStrNDup(pE->token.z, pE->token.n);
sqliteDequote(zLabel);
if( sqliteStrICmp(zName, zLabel)==0 ){
iCol = j;
}
sqliteFree(zLabel);
}
if( iCol<0 && sqliteExprCompare(pE, pEList->a[j].pExpr) ){
iCol = j;
}
}
if( iCol>=0 ){
pE->op = TK_COLUMN;
pE->iColumn = iCol;
pE->iTable = iTable;
pOrderBy->a[i].done = 1;
}
if( iCol<0 && 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.
**
** "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 */
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;
/* Create the destination temporary table if necessary
*/
if( eDest==SRT_TempTable ){
sqliteVdbeAddOp(v, OP_OpenTemp, iParm, 0);
eDest = SRT_Table;
}
/* Generate code for the left and right SELECT statements.
*/
base = pParse->nTab;
switch( p->op ){
case TK_ALL: {
if( p->pOrderBy==0 ){
rc = sqliteSelect(pParse, pPrior, eDest, iParm, 0, 0, 0);
if( rc ) return rc;
p->pPrior = 0;
rc = sqliteSelect(pParse, p, eDest, iParm, 0, 0, 0);
p->pPrior = pPrior;
if( rc ) return rc;
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; /* 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 && p->pOrderBy==0 ){
/* 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( 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, 0, 0, 0);
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;
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 || unionTab!=iParm ){
int iCont, iBreak, iStart;
assert( p->pEList );
if( eDest==SRT_Callback ){
generateColumnNames(pParse, p->base, 0, p->pEList);
}
iBreak = sqliteVdbeMakeLabel(v);
iCont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_Rewind, unionTab, iBreak);
iStart = sqliteVdbeCurrentAddr(v);
rc = selectInnerLoop(pParse, p, 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(p, v, p->pEList->nExpr, eDest, iParm);
}
}
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, 0, 0, 0);
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, 0, 0, 0);
p->pPrior = pPrior;
if( rc ) return rc;
/* Generate code to take the intersection of the two temporary
** tables.
*/
assert( p->pEList );
if( eDest==SRT_Callback ){
generateColumnNames(pParse, p->base, 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, p, 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(p, v, p->pEList->nExpr, eDest, iParm);
}
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;
}
/*
** Recursively scan through an expression tree. For every reference
** to a column in table number iFrom, change that reference to the
** same column in table number iTo.
*/
static void changeTables(Expr *pExpr, int iFrom, int iTo){
if( pExpr==0 ) return;
if( pExpr->op==TK_COLUMN && pExpr->iTable==iFrom ){
pExpr->iTable = iTo;
}else{
static void changeTablesInList(ExprList*, int, int);
changeTables(pExpr->pLeft, iFrom, iTo);
changeTables(pExpr->pRight, iFrom, iTo);
changeTablesInList(pExpr->pList, iFrom, iTo);
}
}
static void changeTablesInList(ExprList *pList, int iFrom, int iTo){
if( pList ){
int i;
for(i=0; i<pList->nExpr; i++){
changeTables(pList->a[i].pExpr, iFrom, iTo);
}
}
}
/*
** Scan through the expression pExpr. Replace every reference to
** a column in table number iTable with a copy of the corresponding
** entry in pEList. (But leave references to the ROWID column
** unchanged.) When making a copy of an expression in pEList, change
** references to columns in table iSub into references to table iTable.
**
** 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 substExpr(Expr *pExpr, int iTable, ExprList *pEList, int iSub){
if( pExpr==0 ) return;
if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable && pExpr->iColumn>=0 ){
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;
pExpr->pLeft = sqliteExprDup(pNew->pLeft);
pExpr->pRight = sqliteExprDup(pNew->pRight);
pExpr->pList = sqliteExprListDup(pNew->pList);
pExpr->iTable = pNew->iTable;
pExpr->iColumn = pNew->iColumn;
pExpr->iAgg = pNew->iAgg;
pExpr->token = pNew->token;
if( iSub!=iTable ){
changeTables(pExpr, iSub, iTable);
}
}else{
static void substExprList(ExprList*,int,ExprList*,int);
substExpr(pExpr->pLeft, iTable, pEList, iSub);
substExpr(pExpr->pRight, iTable, pEList, iSub);
substExprList(pExpr->pList, iTable, pEList, iSub);
}
}
static void
substExprList(ExprList *pList, int iTable, ExprList *pEList, int iSub){
int i;
if( pList==0 ) return;
for(i=0; i<pList->nExpr; i++){
substExpr(pList->a[i].pExpr, iTable, pEList, iSub);
}
}
/*
** 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 a join.
**
** (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.
**
** 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 return 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.
*/
int flattenSubquery(Select *p, int iFrom, int isAgg, int subqueryIsAgg){
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 i;
int iParent, iSub;
Expr *pWhere;
/* 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 );
pSub = pSrc->a[iFrom].pSelect;
assert( pSub!=0 );
if( isAgg && subqueryIsAgg ) return 0;
if( subqueryIsAgg && pSrc->nSrc>1 ) return 0;
pSubSrc = pSub->pSrc;
assert( pSubSrc );
if( pSubSrc->nSrc!=1 ) return 0;
if( (pSub->isDistinct || pSub->nLimit>=0) && (pSrc->nSrc>1 || isAgg) ){
return 0;
}
if( (p->isDistinct || p->nLimit>=0) && subqueryIsAgg ) return 0;
/* If we reach this point, it means flattening is permitted for the
** i-th entry of the FROM clause in the outer query.
*/
iParent = p->base + iFrom;
iSub = pSub->base;
substExprList(p->pEList, iParent, pSub->pEList, iSub);
pList = p->pEList;
for(i=0; i<pList->nExpr; i++){
if( pList->a[i].zName==0 ){
Expr *pExpr = pList->a[i].pExpr;
pList->a[i].zName = sqliteStrNDup(pExpr->span.z, pExpr->span.n);
}
}
if( isAgg ){
substExprList(p->pGroupBy, iParent, pSub->pEList, iSub);
substExpr(p->pHaving, iParent, pSub->pEList, iSub);
}
substExprList(p->pOrderBy, iParent, pSub->pEList, iSub);
if( pSub->pWhere ){
pWhere = sqliteExprDup(pSub->pWhere);
if( iParent!=iSub ){
changeTables(pWhere, iSub, iParent);
}
}else{
pWhere = 0;
}
if( subqueryIsAgg ){
assert( p->pHaving==0 );
p->pHaving = p->pWhere;
p->pWhere = pWhere;
substExpr(p->pHaving, iParent, pSub->pEList, iSub);
if( pSub->pHaving ){
Expr *pHaving = sqliteExprDup(pSub->pHaving);
if( iParent!=iSub ){
changeTables(pHaving, iSub, iParent);
}
if( p->pHaving ){
p->pHaving = sqliteExpr(TK_AND, p->pHaving, pHaving, 0);
}else{
p->pHaving = pHaving;
}
}
assert( p->pGroupBy==0 );
p->pGroupBy = sqliteExprListDup(pSub->pGroupBy);
if( iParent!=iSub ){
changeTablesInList(p->pGroupBy, iSub, iParent);
}
}else if( p->pWhere==0 ){
p->pWhere = pWhere;
}else{
substExpr(p->pWhere, iParent, pSub->pEList, iSub);
if( pWhere ){
p->pWhere = sqliteExpr(TK_AND, p->pWhere, pWhere, 0);
}
}
p->isDistinct = p->isDistinct || pSub->isDistinct;
if( pSub->nLimit>=0 ){
if( p->nLimit<0 ){
p->nLimit = pSub->nLimit;
}else if( p->nLimit+p->nOffset > pSub->nLimit+pSub->nOffset ){
p->nLimit = pSub->nLimit + pSub->nOffset - p->nOffset;
}
}
p->nOffset += pSub->nOffset;
if( pSrc->a[iFrom].pTab && pSrc->a[iFrom].pTab->isTransient ){
sqliteDeleteTable(0, pSrc->a[iFrom].pTab);
}
pSrc->a[iFrom].pTab = pSubSrc->a[0].pTab;
pSubSrc->a[0].pTab = 0;
pSrc->a[iFrom].pSelect = pSubSrc->a[0].pSelect;
pSubSrc->a[0].pSelect = 0;
sqliteSelectDelete(pSub);
return 1;
}
/*
** 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->nSrc!=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->token.n!=3 ) return 0;
if( sqliteStrNICmp(pExpr->token.z,"min",3)==0 ){
seekOp = OP_Rewind;
}else if( sqliteStrNICmp(pExpr->token.z,"max",3)==0 ){
seekOp = OP_Last;
}else{
return 0;
}
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 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{
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 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->base, p->pSrc, p->pEList);
}
/* 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.
*/
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 = p->base;
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, p, &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.
**
** 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.
*/
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 */
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 */
){
int i;
WhereInfo *pWInfo;
Vdbe *v;
int isAgg = 0; /* 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 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;
/* Allocate a block of VDBE cursors, one for each table in the FROM clause.
** The WHERE processing requires that the cursors for the tables in the
** FROM clause be consecutive.
*/
base = p->base = pParse->nTab;
pParse->nTab += pTabList->nSrc;
/*
** 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;
}
pWhere = p->pWhere;
pEList = p->pEList;
if( pEList==0 ) goto select_end;
/* 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 for some destinations.
*/
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
** need to handle subquerys and temporary tables.
**
** Resolve the column names and do a semantics check on all the expressions.
*/
for(i=0; i<pEList->nExpr; i++){
if( sqliteExprResolveIds(pParse, base, 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, base, 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) ){
int iCol;
if( sqliteExprIsInteger(pE, &iCol)==0 ){
sqliteSetString(&pParse->zErrMsg,
"ORDER BY terms must not be non-integer constants", 0);
pParse->nErr++;
goto select_end;
}else if( iCol<=0 || iCol>pEList->nExpr ){
char zBuf[2000];
sprintf(zBuf,"ORDER BY column number %d out of range - should be "
"between 1 and %d", iCol, pEList->nExpr);
sqliteSetString(&pParse->zErrMsg, zBuf, 0);
pParse->nErr++;
goto select_end;
}
sqliteExprDelete(pE);
pE = pOrderBy->a[i].pExpr = sqliteExprDup(pEList->a[iCol-1].pExpr);
}
if( sqliteExprResolveIds(pParse, base, 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, base, 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, base, 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;
/* 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, p->base, pTabList, pEList);
}
/* Set the limiter
*/
if( p->nLimit<=0 ){
p->nLimit = -1;
p->nOffset = 0;
}else{
int iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_Integer, -p->nLimit, 0);
sqliteVdbeAddOp(v, OP_MemStore, iMem, 1);
p->nLimit = iMem;
if( p->nOffset<=0 ){
p->nOffset = 0;
}else{
iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_Integer, -p->nOffset, 0);
sqliteVdbeAddOp(v, OP_MemStore, iMem, 1);
p->nOffset = iMem;
}
}
/* Generate code for all sub-queries in the FROM clause
*/
for(i=0; i<pTabList->nSrc; i++){
if( pTabList->a[i].pSelect==0 ) continue;
sqliteSelect(pParse, pTabList->a[i].pSelect, SRT_TempTable, base+i,
p, i, &isAgg);
pTabList = p->pSrc;
pWhere = p->pWhere;
if( eDest==SRT_Callback ){
pOrderBy = p->pOrderBy;
}
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
isDistinct = p->isDistinct;
}
/* 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.
*/
if( pParent && pParentAgg &&
flattenSubquery(pParent, parentTab, *pParentAgg, isAgg) ){
if( isAgg ) *pParentAgg = 1;
return rc;
}
/* If the output is destined for a temporary table, open that table.
*/
if( eDest==SRT_TempTable ){
sqliteVdbeAddOp(v, OP_OpenTemp, iParm, 0);
}
/* Do an analysis of aggregate expressions.
*/
sqliteAggregateInfoReset(pParse);
if( isAgg ){
assert( pParse->nAgg==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;
}
}
}
}
/* Reset the aggregator
*/
if( isAgg ){
sqliteVdbeAddOp(v, OP_AggReset, 0, pParse->nAgg);
for(i=0; i<pParse->nAgg; i++){
FuncDef *pFunc;
if( (pFunc = pParse->aAgg[i].pFunc)!=0 && pFunc->xFinalize!=0 ){
sqliteVdbeAddOp(v, OP_AggInit, 0, i);
sqliteVdbeChangeP3(v, -1, (char*)pFunc, P3_POINTER);
}
}
if( pGroupBy==0 ){
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_AggFocus, 0, 0);
}
}
/* Initialize the memory cell to NULL
*/
if( eDest==SRT_Mem ){
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, iParm, 1);
}
/* Open a temporary table to use for the distinct set.
*/
if( isDistinct ){
distinct = pParse->nTab++;
sqliteVdbeAddOp(v, OP_OpenTemp, distinct, 1);
}else{
distinct = -1;
}
/* Begin the database scan
*/
pWInfo = sqliteWhereBegin(pParse, p->base, pTabList, pWhere, 0, &pOrderBy);
if( pWInfo==0 ) goto select_end;
/* Use the standard inner loop if we are not dealing with
** aggregates
*/
if( !isAgg ){
if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
iParm, pWInfo->iContinue, pWInfo->iBreak) ){
goto select_end;
}
}
/* If we are dealing with aggregates, then do 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 j;
if( !pParse->aAgg[i].isAgg ) continue;
pE = pParse->aAgg[i].pExpr;
assert( pE->op==TK_AGG_FUNCTION );
if( pE->pList ){
for(j=0; j<pE->pList->nExpr; j++){
sqliteExprCode(pParse, pE->pList->a[j].pExpr);
}
}
sqliteVdbeAddOp(v, OP_Integer, i, 0);
sqliteVdbeAddOp(v, OP_AggFunc, 0, pE->pList ? pE->pList->nExpr : 0);
assert( pParse->aAgg[i].pFunc!=0 );
assert( pParse->aAgg[i].pFunc->xStep!=0 );
sqliteVdbeChangeP3(v, -1, (char*)pParse->aAgg[i].pFunc, P3_POINTER);
}
}
/* 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, 1);
}
if( selectInnerLoop(pParse, p, 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(p, v, pEList->nExpr, eDest, iParm);
}
/* 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:
pParse->nTab = base;
sqliteAggregateInfoReset(pParse);
return rc;
}