/*
** Process a DELETE FROM statement.
*/
void sqliteDeleteFrom(
Parse *pParse, /* The parser context */
SrcList *pTabList, /* The table from which we should delete things */
Expr *pWhere /* The WHERE clause. May be null */
){
Vdbe *v; /* The virtual database engine */
Table *pTab; /* The table from which records will be deleted */
const char *zDb; /* Name of database holding pTab */
int end, addr; /* A couple addresses of generated code */
int i; /* Loop counter */
WhereInfo *pWInfo; /* Information about the WHERE clause */
Index *pIdx; /* For looping over indices of the table */
int iCur; /* VDBE Cursor number for pTab */
sqlite *db; /* Main database structure */
int isView; /* True if attempting to delete from a view */
AuthContext sContext; /* Authorization context */
int row_triggers_exist = 0; /* True if any triggers exist */
int before_triggers; /* True if there are BEFORE triggers */
int after_triggers; /* True if there are AFTER triggers */
int oldIdx = -1; /* Cursor for the OLD table of AFTER triggers */
sContext.pParse = 0;
if( pParse->nErr || sqlite_malloc_failed ){
pTabList = 0;
goto delete_from_cleanup;
}
db = pParse->db;
assert( pTabList->nSrc==1 );
/* Locate the table which we want to delete. This table has to be
** put in an SrcList structure because some of the subroutines we
** will be calling are designed to work with multiple tables and expect
** an SrcList* parameter instead of just a Table* parameter.
*/
pTab = sqliteSrcListLookup(pParse, pTabList);
if( pTab==0 ) goto delete_from_cleanup;
before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
TK_DELETE, TK_BEFORE, TK_ROW, 0);
after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger,
TK_DELETE, TK_AFTER, TK_ROW, 0);
row_triggers_exist = before_triggers || after_triggers;
isView = pTab->pSelect!=0;
if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){
goto delete_from_cleanup;
}
assert( pTab->iDb<db->nDb );
zDb = db->aDb[pTab->iDb].zName;
if( sqliteAuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){
goto delete_from_cleanup;
}
/* If pTab is really a view, make sure it has been initialized.
*/
if( isView && sqliteViewGetColumnNames(pParse, pTab) ){
goto delete_from_cleanup;
}
/* Allocate a cursor used to store the old.* data for a trigger.
*/
if( row_triggers_exist ){
oldIdx = pParse->nTab++;
}
/* Resolve the column names in all the expressions.
*/
assert( pTabList->nSrc==1 );
iCur = pTabList->a[0].iCursor = pParse->nTab++;
if( pWhere ){
if( sqliteExprResolveIds(pParse, pTabList, 0, pWhere) ){
goto delete_from_cleanup;
}
if( sqliteExprCheck(pParse, pWhere, 0, 0) ){
goto delete_from_cleanup;
}
}
/* Start the view context
*/
if( isView ){
sqliteAuthContextPush(pParse, &sContext, pTab->zName);
}
/* Begin generating code.
*/
v = sqliteGetVdbe(pParse);
if( v==0 ){
goto delete_from_cleanup;
}
sqliteBeginWriteOperation(pParse, row_triggers_exist, pTab->iDb);
/* If we are trying to delete from a view, construct that view into
** a temporary table.
*/
if( isView ){
Select *pView = sqliteSelectDup(pTab->pSelect);
sqliteSelect(pParse, pView, SRT_TempTable, iCur, 0, 0, 0);
sqliteSelectDelete(pView);
}
/* Initialize the counter of the number of rows deleted, if
** we are counting rows.
*/
if( db->flags & SQLITE_CountRows ){
sqliteVdbeAddOp(v, OP_Integer, 0, 0);
}
/* Special case: A DELETE without a WHERE clause deletes everything.
** It is easier just to erase the whole table. Note, however, that
** this means that the row change count will be incorrect.
*/
if( pWhere==0 && !row_triggers_exist ){
if( db->flags & SQLITE_CountRows ){
/* If counting rows deleted, just count the total number of
** entries in the table. */
int endOfLoop = sqliteVdbeMakeLabel(v);
int addr;
if( !isView ){
sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum);
}
sqliteVdbeAddOp(v, OP_Rewind, iCur, sqliteVdbeCurrentAddr(v)+2);
addr = sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
sqliteVdbeAddOp(v, OP_Next, iCur, addr);
sqliteVdbeResolveLabel(v, endOfLoop);
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
}
if( !isView ){
sqliteVdbeAddOp(v, OP_Clear, pTab->tnum, pTab->iDb);
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
sqliteVdbeAddOp(v, OP_Clear, pIdx->tnum, pIdx->iDb);
}
}
}
/* The usual case: There is a WHERE clause so we have to scan through
** the table and pick which records to delete.
*/
else{
/* Begin the database scan
*/
pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1, 0);
if( pWInfo==0 ) goto delete_from_cleanup;
/* Remember the key of every item to be deleted.
*/
sqliteVdbeAddOp(v, OP_ListWrite, 0, 0);
if( db->flags & SQLITE_CountRows ){
sqliteVdbeAddOp(v, OP_AddImm, 1, 0);
}
/* End the database scan loop.
*/
sqliteWhereEnd(pWInfo);
/* Open the pseudo-table used to store OLD if there are triggers.
*/
if( row_triggers_exist ){
sqliteVdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
}
/* Delete every item whose key was written to the list during the
** database scan. We have to delete items after the scan is complete
** because deleting an item can change the scan order.
*/
sqliteVdbeAddOp(v, OP_ListRewind, 0, 0);
end = sqliteVdbeMakeLabel(v);
/* This is the beginning of the delete loop when there are
** row triggers.
*/
if( row_triggers_exist ){
addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
if( !isView ){
sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum);
}
sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
sqliteVdbeAddOp(v, OP_RowData, iCur, 0);
sqliteVdbeAddOp(v, OP_PutIntKey, oldIdx, 0);
if( !isView ){
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
}
sqliteCodeRowTrigger(pParse, TK_DELETE, 0, TK_BEFORE, pTab, -1,
oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
addr);
}
if( !isView ){
/* Open cursors for the table we are deleting from and all its
** indices. If there are row triggers, this happens inside the
** OP_ListRead loop because the cursor have to all be closed
** before the trigger fires. If there are no row triggers, the
** cursors are opened only once on the outside the loop.
*/
pParse->nTab = iCur + 1;
sqliteOpenTableAndIndices(pParse, pTab, iCur);
/* This is the beginning of the delete loop when there are no
** row triggers */
if( !row_triggers_exist ){
addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end);
}
/* Delete the row */
sqliteGenerateRowDelete(db, v, pTab, iCur, pParse->trigStack==0);
}
/* If there are row triggers, close all cursors then invoke
** the AFTER triggers
*/
if( row_triggers_exist ){
if( !isView ){
for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
sqliteVdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
}
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
}
sqliteCodeRowTrigger(pParse, TK_DELETE, 0, TK_AFTER, pTab, -1,
oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default,
addr);
}
/* End of the delete loop */
sqliteVdbeAddOp(v, OP_Goto, 0, addr);
sqliteVdbeResolveLabel(v, end);
sqliteVdbeAddOp(v, OP_ListReset, 0, 0);
/* Close the cursors after the loop if there are no row triggers */
if( !row_triggers_exist ){
for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
sqliteVdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum);
}
sqliteVdbeAddOp(v, OP_Close, iCur, 0);
pParse->nTab = iCur;
}
}
sqliteVdbeAddOp(v, OP_SetCounts, 0, 0);
sqliteEndWriteOperation(pParse);
/*
** Return the number of rows that were deleted.
*/
if( db->flags & SQLITE_CountRows ){
sqliteVdbeAddOp(v, OP_ColumnName, 0, 1);
sqliteVdbeChangeP3(v, -1, "rows deleted", P3_STATIC);
sqliteVdbeAddOp(v, OP_Callback, 1, 0);
}
delete_from_cleanup:
sqliteAuthContextPop(&sContext);
sqliteSrcListDelete(pTabList);
sqliteExprDelete(pWhere);
return;
}
/*
** Generate code to do a constraint check prior to an INSERT or an UPDATE.
**
** When this routine is called, the stack contains (from bottom to top)
** the following values:
**
** 1. The recno of the row to be updated before the update. This
** value is omitted unless we are doing an UPDATE that involves a
** change to the record number.
**
** 2. The recno of the row after the update.
**
** 3. The data in the first column of the entry after the update.
**
** i. Data from middle columns...
**
** N. The data in the last column of the entry after the update.
**
** The old recno shown as entry (1) above is omitted unless both isUpdate
** and recnoChng are 1. isUpdate is true for UPDATEs and false for
** INSERTs and recnoChng is true if the record number is being changed.
**
** The code generated by this routine pushes additional entries onto
** the stack which are the keys for new index entries for the new record.
** The order of index keys is the same as the order of the indices on
** the pTable->pIndex list. A key is only created for index i if
** aIdxUsed!=0 and aIdxUsed[i]!=0.
**
** This routine also generates code to check constraints. NOT NULL,
** CHECK, and UNIQUE constraints are all checked. If a constraint fails,
** then the appropriate action is performed. There are five possible
** actions: ROLLBACK, ABORT, FAIL, REPLACE, and IGNORE.
**
** Constraint type Action What Happens
** --------------- ---------- ----------------------------------------
** any ROLLBACK The current transaction is rolled back and
** sqlite_exec() returns immediately with a
** return code of SQLITE_CONSTRAINT.
**
** any ABORT Back out changes from the current command
** only (do not do a complete rollback) then
** cause sqlite_exec() to return immediately
** with SQLITE_CONSTRAINT.
**
** any FAIL Sqlite_exec() returns immediately with a
** return code of SQLITE_CONSTRAINT. The
** transaction is not rolled back and any
** prior changes are retained.
**
** any IGNORE The record number and data is popped from
** the stack and there is an immediate jump
** to label ignoreDest.
**
** NOT NULL REPLACE The NULL value is replace by the default
** value for that column. If the default value
** is NULL, the action is the same as ABORT.
**
** UNIQUE REPLACE The other row that conflicts with the row
** being inserted is removed.
**
** CHECK REPLACE Illegal. The results in an exception.
**
** Which action to take is determined by the overrideError parameter.
** Or if overrideError==OE_Default, then the pParse->onError parameter
** is used. Or if pParse->onError==OE_Default then the onError value
** for the constraint is used.
**
** The calling routine must open a read/write cursor for pTab with
** cursor number "base". All indices of pTab must also have open
** read/write cursors with cursor number base+i for the i-th cursor.
** Except, if there is no possibility of a REPLACE action then
** cursors do not need to be open for indices where aIdxUsed[i]==0.
**
** If the isUpdate flag is true, it means that the "base" cursor is
** initially pointing to an entry that is being updated. The isUpdate
** flag causes extra code to be generated so that the "base" cursor
** is still pointing at the same entry after the routine returns.
** Without the isUpdate flag, the "base" cursor might be moved.
*/
void sqliteGenerateConstraintChecks(
Parse *pParse, /* The parser context */
Table *pTab, /* the table into which we are inserting */
int base, /* Index of a read/write cursor pointing at pTab */
char *aIdxUsed, /* Which indices are used. NULL means all are used */
int recnoChng, /* True if the record number will change */
int isUpdate, /* True for UPDATE, False for INSERT */
int overrideError, /* Override onError to this if not OE_Default */
int ignoreDest /* Jump to this label on an OE_Ignore resolution */
){
int i;
Vdbe *v;
int nCol;
int onError;
int addr;
int extra;
int iCur;
Index *pIdx;
int seenReplace = 0;
int jumpInst1, jumpInst2;
int contAddr;
int hasTwoRecnos = (isUpdate && recnoChng);
v = sqliteGetVdbe(pParse);
assert( v!=0 );
assert( pTab->pSelect==0 ); /* This table is not a VIEW */
nCol = pTab->nCol;
/* Test all NOT NULL constraints.
*/
for(i=0; i<nCol; i++){
if( i==pTab->iPKey ){
continue;
}
onError = pTab->aCol[i].notNull;
if( onError==OE_None ) continue;
if( overrideError!=OE_Default ){
onError = overrideError;
}else if( pParse->db->onError!=OE_Default ){
onError = pParse->db->onError;
}else if( onError==OE_Default ){
onError = OE_Abort;
}
if( onError==OE_Replace && pTab->aCol[i].zDflt==0 ){
onError = OE_Abort;
}
sqliteVdbeAddOp(v, OP_Dup, nCol-1-i, 1);
addr = sqliteVdbeAddOp(v, OP_NotNull, 1, 0);
switch( onError ){
case OE_Rollback:
case OE_Abort:
case OE_Fail: {
char *zMsg = 0;
sqliteVdbeAddOp(v, OP_Halt, SQLITE_CONSTRAINT, onError);
sqliteSetString(&zMsg, pTab->zName, ".", pTab->aCol[i].zName,
" may not be NULL", (char*)0);
sqliteVdbeChangeP3(v, -1, zMsg, P3_DYNAMIC);
break;
}
case OE_Ignore: {
sqliteVdbeAddOp(v, OP_Pop, nCol+1+hasTwoRecnos, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, ignoreDest);
break;
}
case OE_Replace: {
sqliteVdbeOp3(v, OP_String, 0, 0, pTab->aCol[i].zDflt, P3_STATIC);
sqliteVdbeAddOp(v, OP_Push, nCol-i, 0);
break;
}
default: assert(0);
}
sqliteVdbeChangeP2(v, addr, sqliteVdbeCurrentAddr(v));
}
/* Test all CHECK constraints
*/
/**** TBD ****/
/* If we have an INTEGER PRIMARY KEY, make sure the primary key
** of the new record does not previously exist. Except, if this
** is an UPDATE and the primary key is not changing, that is OK.
*/
if( recnoChng ){
onError = pTab->keyConf;
if( overrideError!=OE_Default ){
onError = overrideError;
}else if( pParse->db->onError!=OE_Default ){
onError = pParse->db->onError;
}else if( onError==OE_Default ){
onError = OE_Abort;
}
if( isUpdate ){
sqliteVdbeAddOp(v, OP_Dup, nCol+1, 1);
sqliteVdbeAddOp(v, OP_Dup, nCol+1, 1);
jumpInst1 = sqliteVdbeAddOp(v, OP_Eq, 0, 0);
}
sqliteVdbeAddOp(v, OP_Dup, nCol, 1);
jumpInst2 = sqliteVdbeAddOp(v, OP_NotExists, base, 0);
switch( onError ){
default: {
onError = OE_Abort;
/* Fall thru into the next case */
}
case OE_Rollback:
case OE_Abort:
case OE_Fail: {
sqliteVdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, onError,
"PRIMARY KEY must be unique", P3_STATIC);
break;
}
case OE_Replace: {
sqliteGenerateRowIndexDelete(pParse->db, v, pTab, base, 0);
if( isUpdate ){
sqliteVdbeAddOp(v, OP_Dup, nCol+hasTwoRecnos, 1);
sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
}
seenReplace = 1;
break;
}
case OE_Ignore: {
assert( seenReplace==0 );
sqliteVdbeAddOp(v, OP_Pop, nCol+1+hasTwoRecnos, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, ignoreDest);
break;
}
}
contAddr = sqliteVdbeCurrentAddr(v);
sqliteVdbeChangeP2(v, jumpInst2, contAddr);
if( isUpdate ){
sqliteVdbeChangeP2(v, jumpInst1, contAddr);
sqliteVdbeAddOp(v, OP_Dup, nCol+1, 1);
sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
}
}
/* Test all UNIQUE constraints by creating entries for each UNIQUE
** index and making sure that duplicate entries do not already exist.
** Add the new records to the indices as we go.
*/
extra = -1;
for(iCur=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, iCur++){
if( aIdxUsed && aIdxUsed[iCur]==0 ) continue; /* Skip unused indices */
extra++;
/* Create a key for accessing the index entry */
sqliteVdbeAddOp(v, OP_Dup, nCol+extra, 1);
for(i=0; i<pIdx->nColumn; i++){
int idx = pIdx->aiColumn[i];
if( idx==pTab->iPKey ){
sqliteVdbeAddOp(v, OP_Dup, i+extra+nCol+1, 1);
}else{
sqliteVdbeAddOp(v, OP_Dup, i+extra+nCol-idx, 1);
}
}
jumpInst1 = sqliteVdbeAddOp(v, OP_MakeIdxKey, pIdx->nColumn, 0);
if( pParse->db->file_format>=4 ) sqliteAddIdxKeyType(v, pIdx);
/* Find out what action to take in case there is an indexing conflict */
onError = pIdx->onError;
if( onError==OE_None ) continue; /* pIdx is not a UNIQUE index */
if( overrideError!=OE_Default ){
onError = overrideError;
}else if( pParse->db->onError!=OE_Default ){
onError = pParse->db->onError;
}else if( onError==OE_Default ){
onError = OE_Abort;
}
if( seenReplace ){
if( onError==OE_Ignore ) onError = OE_Replace;
else if( onError==OE_Fail ) onError = OE_Abort;
}
/* Check to see if the new index entry will be unique */
sqliteVdbeAddOp(v, OP_Dup, extra+nCol+1+hasTwoRecnos, 1);
jumpInst2 = sqliteVdbeAddOp(v, OP_IsUnique, base+iCur+1, 0);
/* Generate code that executes if the new index entry is not unique */
switch( onError ){
case OE_Rollback:
case OE_Abort:
case OE_Fail: {
int j, n1, n2;
char zErrMsg[200];
strcpy(zErrMsg, pIdx->nColumn>1 ? "columns " : "column ");
n1 = strlen(zErrMsg);
for(j=0; j<pIdx->nColumn && n1<sizeof(zErrMsg)-30; j++){
char *zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
n2 = strlen(zCol);
if( j>0 ){
strcpy(&zErrMsg[n1], ", ");
n1 += 2;
}
if( n1+n2>sizeof(zErrMsg)-30 ){
strcpy(&zErrMsg[n1], "...");
n1 += 3;
break;
}else{
strcpy(&zErrMsg[n1], zCol);
n1 += n2;
}
}
strcpy(&zErrMsg[n1],
pIdx->nColumn>1 ? " are not unique" : " is not unique");
sqliteVdbeOp3(v, OP_Halt, SQLITE_CONSTRAINT, onError, zErrMsg, 0);
break;
}
case OE_Ignore: {
assert( seenReplace==0 );
sqliteVdbeAddOp(v, OP_Pop, nCol+extra+3+hasTwoRecnos, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, ignoreDest);
break;
}
case OE_Replace: {
sqliteGenerateRowDelete(pParse->db, v, pTab, base, 0);
if( isUpdate ){
sqliteVdbeAddOp(v, OP_Dup, nCol+extra+1+hasTwoRecnos, 1);
sqliteVdbeAddOp(v, OP_MoveTo, base, 0);
}
seenReplace = 1;
break;
}
default: assert(0);
}
contAddr = sqliteVdbeCurrentAddr(v);
#if NULL_DISTINCT_FOR_UNIQUE
sqliteVdbeChangeP2(v, jumpInst1, contAddr);
#endif
sqliteVdbeChangeP2(v, jumpInst2, contAddr);
}
}
