?? select.c
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sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
sqlite3VdbeJumpHere(v, addr2);
pSelect->iLimit = -1;
}
}
/*
** Add code to implement the OFFSET
*/
static void codeOffset(
Vdbe *v, /* Generate code into this VM */
Select *p, /* The SELECT statement being coded */
int iContinue, /* Jump here to skip the current record */
int nPop /* Number of times to pop stack when jumping */
){
if( p->iOffset>=0 && iContinue!=0 ){
int addr;
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iOffset);
addr = sqlite3VdbeAddOp(v, OP_IfMemNeg, p->iOffset, 0);
if( nPop>0 ){
sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
}
sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
VdbeComment((v, "# skip OFFSET records"));
sqlite3VdbeJumpHere(v, addr);
}
}
/*
** Add code that will check to make sure the top N elements of the
** stack are distinct. iTab is a sorting index that holds previously
** seen combinations of the N values. A new entry is made in iTab
** if the current N values are new.
**
** A jump to addrRepeat is made and the N+1 values are popped from the
** stack if the top N elements are not distinct.
*/
static void codeDistinct(
Vdbe *v, /* Generate code into this VM */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
int N /* The top N elements of the stack must be distinct */
){
sqlite3VdbeAddOp(v, OP_MakeRecord, -N, 0);
sqlite3VdbeAddOp(v, OP_Distinct, iTab, sqlite3VdbeCurrentAddr(v)+3);
sqlite3VdbeAddOp(v, OP_Pop, N+1, 0);
sqlite3VdbeAddOp(v, OP_Goto, 0, addrRepeat);
VdbeComment((v, "# skip indistinct records"));
sqlite3VdbeAddOp(v, OP_IdxInsert, iTab, 0);
}
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab and nColumn are both zero, then the pEList expressions
** are evaluated in order to get the data for this row. If nColumn>0
** then data is pulled from srcTab and pEList is used only to get the
** datatypes for each column.
*/
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 */
char *aff /* affinity string if eDest is SRT_Union */
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
if( v==0 ) return 0;
assert( pEList!=0 );
/* If there was a LIMIT clause on the SELECT statement, then do the check
** to see if this row should be output.
*/
hasDistinct = distinct>=0 && pEList->nExpr>0;
if( pOrderBy==0 && !hasDistinct ){
codeOffset(v, p, iContinue, 0);
}
/* Pull the requested columns.
*/
if( nColumn>0 ){
for(i=0; i<nColumn; i++){
sqlite3VdbeAddOp(v, OP_Column, srcTab, i);
}
}else{
nColumn = pEList->nExpr;
sqlite3ExprCodeExprList(pParse, pEList);
}
/* 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( hasDistinct ){
assert( pEList!=0 );
assert( pEList->nExpr==nColumn );
codeDistinct(v, distinct, iContinue, nColumn);
if( pOrderBy==0 ){
codeOffset(v, p, iContinue, nColumn);
}
}
switch( eDest ){
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
case SRT_Union: {
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
if( aff ){
sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
}
sqlite3VdbeAddOp(v, OP_IdxInsert, 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 = sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
sqlite3VdbeAddOp(v, OP_NotFound, iParm, addr+3);
sqlite3VdbeAddOp(v, OP_Delete, iParm, 0);
break;
}
#endif
/* Store the result as data using a unique key.
*/
case SRT_Table:
case SRT_EphemTab: {
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p);
}else{
sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
}
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* 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: {
int addr1 = sqlite3VdbeCurrentAddr(v);
int addr2;
assert( nColumn==1 );
sqlite3VdbeAddOp(v, OP_NotNull, -1, addr1+3);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
if( pOrderBy ){
/* At first glance you would think we could optimize out the
** ORDER BY in this case since the order of entries in the set
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter(pParse, pOrderBy, p);
}else{
char affinity = (iParm>>16)&0xFF;
affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, affinity);
sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1);
sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
}
sqlite3VdbeJumpHere(v, addr2);
break;
}
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp(v, OP_MemInt, 1, iParm);
sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
/* The LIMIT clause will terminate the loop for us */
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, pOrderBy, p);
}else{
sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
/* The LIMIT clause will jump out of the loop for us */
}
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
/* Send the data to the callback function or to a subroutine. In the
** case of a subroutine, the subroutine itself is responsible for
** popping the data from the stack.
*/
case SRT_Subroutine:
case SRT_Callback: {
if( pOrderBy ){
sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
pushOntoSorter(pParse, pOrderBy, p);
}else if( eDest==SRT_Subroutine ){
sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
}else{
sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
}
break;
}
#if !defined(SQLITE_OMIT_TRIGGER)
/* 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 );
sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit>=0 && pOrderBy==0 ){
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
}
return 0;
}
/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.
**
** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
** KeyInfo structure is appropriate for initializing a virtual index to
** implement that clause. If the ExprList is the result set of a SELECT
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc. The calling
** function is responsible for seeing that this structure is eventually
** freed. Add the KeyInfo structure to the P3 field of an opcode using
** P3_KEYINFO_HANDOFF is the usual way of dealing with this.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
sqlite3 *db = pParse->db;
int nExpr;
KeyInfo *pInfo;
struct ExprList_item *pItem;
int i;
nExpr = pList->nExpr;
pInfo = sqliteMalloc( sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
if( pInfo ){
pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
pInfo->nField = nExpr;
pInfo->enc = ENC(db);
for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
CollSeq *pColl;
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
if( !pColl ){
pColl = db->pDfltColl;
}
pInfo->aColl[i] = pColl;
pInfo->aSortOrder[i] = pItem->sortOrder;
}
}
return pInfo;
}
/*
** 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(
Parse *pParse, /* Parsing context */
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 brk = sqlite3VdbeMakeLabel(v);
int cont = sqlite3VdbeMakeLabel(v);
int addr;
int iTab;
int pseudoTab;
ExprList *pOrderBy = p->pOrderBy;
iTab = pOrderBy->iECursor;
if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
pseudoTab = pParse->nTab++;
sqlite3VdbeAddOp(v, OP_OpenPseudo, pseudoTab, 0);
sqlite3VdbeAddOp(v, OP_SetNumColumns, pseudoTab, nColumn);
}
addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk);
codeOffset(v, p, cont, 0);
if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
}
sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr + 1);
switch( eDest ){
case SRT_Table:
case SRT_EphemTab: {
sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case SRT_Set: {
assert( nColumn==1 );
sqlite3VdbeAddOp(v, OP_NotNull, -1, sqlite3VdbeCurrentAddr(v)+3);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
sqlite3VdbeAddOp(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+3);
sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, "c", P3_STATIC);
sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
break;
}
case SRT_Mem: {
assert( nColumn==1 );
sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
case SRT_Callback:
case SRT_Subroutine: {
int i;
sqlite3VdbeAddOp(v, OP_Insert, pseudoTab, 0);
for(i=0; i<nColumn; i++){
sqlite3VdbeAddOp(v, OP_Column, pseudoTab, i);
}
if( eDest==SRT_Callback ){
sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
}else{
sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
}
break;
}
default: {
/* Do nothing */
break;
}
}
/* Jump to the end of the loop when the LIMIT is reached
*/
if( p->iLimit>=0 ){
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
}
/* The bottom of the loop
*/
sqlite3VdbeResolveLabel(v, cont);
sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
sqlite3VdbeResolveLabel(v, brk);
if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
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