xref: /sqlite-3.40.0/src/delete.c (revision 5368f29a)
1 /*
2 ** 2001 September 15
3 **
4 ** The author disclaims copyright to this source code.  In place of
5 ** a legal notice, here is a blessing:
6 **
7 **    May you do good and not evil.
8 **    May you find forgiveness for yourself and forgive others.
9 **    May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** This file contains C code routines that are called by the parser
13 ** in order to generate code for DELETE FROM statements.
14 **
15 ** $Id: delete.c,v 1.204 2009/06/23 20:28:54 drh Exp $
16 */
17 #include "sqliteInt.h"
18 
19 /*
20 ** Look up every table that is named in pSrc.  If any table is not found,
21 ** add an error message to pParse->zErrMsg and return NULL.  If all tables
22 ** are found, return a pointer to the last table.
23 */
24 Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
25   struct SrcList_item *pItem = pSrc->a;
26   Table *pTab;
27   assert( pItem && pSrc->nSrc==1 );
28   pTab = sqlite3LocateTable(pParse, 0, pItem->zName, pItem->zDatabase);
29   sqlite3DeleteTable(pItem->pTab);
30   pItem->pTab = pTab;
31   if( pTab ){
32     pTab->nRef++;
33   }
34   if( sqlite3IndexedByLookup(pParse, pItem) ){
35     pTab = 0;
36   }
37   return pTab;
38 }
39 
40 /*
41 ** Check to make sure the given table is writable.  If it is not
42 ** writable, generate an error message and return 1.  If it is
43 ** writable return 0;
44 */
45 int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
46   if( ((pTab->tabFlags & TF_Readonly)!=0
47         && (pParse->db->flags & SQLITE_WriteSchema)==0
48         && pParse->nested==0)
49 #ifndef SQLITE_OMIT_VIRTUALTABLE
50       || (pTab->pMod && pTab->pMod->pModule->xUpdate==0)
51 #endif
52   ){
53     sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
54     return 1;
55   }
56 #ifndef SQLITE_OMIT_VIEW
57   if( !viewOk && pTab->pSelect ){
58     sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
59     return 1;
60   }
61 #endif
62   return 0;
63 }
64 
65 
66 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
67 /*
68 ** Evaluate a view and store its result in an ephemeral table.  The
69 ** pWhere argument is an optional WHERE clause that restricts the
70 ** set of rows in the view that are to be added to the ephemeral table.
71 */
72 void sqlite3MaterializeView(
73   Parse *pParse,       /* Parsing context */
74   Table *pView,        /* View definition */
75   Expr *pWhere,        /* Optional WHERE clause to be added */
76   int iCur             /* Cursor number for ephemerial table */
77 ){
78   SelectDest dest;
79   Select *pDup;
80   sqlite3 *db = pParse->db;
81 
82   pDup = sqlite3SelectDup(db, pView->pSelect, 0);
83   if( pWhere ){
84     SrcList *pFrom;
85 
86     pWhere = sqlite3ExprDup(db, pWhere, 0);
87     pFrom = sqlite3SrcListAppend(db, 0, 0, 0);
88     if( pFrom ){
89       assert( pFrom->nSrc==1 );
90       pFrom->a[0].zAlias = sqlite3DbStrDup(db, pView->zName);
91       pFrom->a[0].pSelect = pDup;
92       assert( pFrom->a[0].pOn==0 );
93       assert( pFrom->a[0].pUsing==0 );
94     }else{
95       sqlite3SelectDelete(db, pDup);
96     }
97     pDup = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, 0, 0, 0);
98   }
99   sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
100   sqlite3Select(pParse, pDup, &dest);
101   sqlite3SelectDelete(db, pDup);
102 }
103 #endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
104 
105 #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
106 /*
107 ** Generate an expression tree to implement the WHERE, ORDER BY,
108 ** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
109 **
110 **     DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
111 **                            \__________________________/
112 **                               pLimitWhere (pInClause)
113 */
114 Expr *sqlite3LimitWhere(
115   Parse *pParse,               /* The parser context */
116   SrcList *pSrc,               /* the FROM clause -- which tables to scan */
117   Expr *pWhere,                /* The WHERE clause.  May be null */
118   ExprList *pOrderBy,          /* The ORDER BY clause.  May be null */
119   Expr *pLimit,                /* The LIMIT clause.  May be null */
120   Expr *pOffset,               /* The OFFSET clause.  May be null */
121   char *zStmtType              /* Either DELETE or UPDATE.  For error messages. */
122 ){
123   Expr *pWhereRowid = NULL;    /* WHERE rowid .. */
124   Expr *pInClause = NULL;      /* WHERE rowid IN ( select ) */
125   Expr *pSelectRowid = NULL;   /* SELECT rowid ... */
126   ExprList *pEList = NULL;     /* Expression list contaning only pSelectRowid */
127   SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
128   Select *pSelect = NULL;      /* Complete SELECT tree */
129 
130   /* Check that there isn't an ORDER BY without a LIMIT clause.
131   */
132   if( pOrderBy && (pLimit == 0) ) {
133     sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
134     pParse->parseError = 1;
135     goto limit_where_cleanup_2;
136   }
137 
138   /* We only need to generate a select expression if there
139   ** is a limit/offset term to enforce.
140   */
141   if( pLimit == 0 ) {
142     /* if pLimit is null, pOffset will always be null as well. */
143     assert( pOffset == 0 );
144     return pWhere;
145   }
146 
147   /* Generate a select expression tree to enforce the limit/offset
148   ** term for the DELETE or UPDATE statement.  For example:
149   **   DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
150   ** becomes:
151   **   DELETE FROM table_a WHERE rowid IN (
152   **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
153   **   );
154   */
155 
156   pSelectRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
157   if( pSelectRowid == 0 ) goto limit_where_cleanup_2;
158   pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid);
159   if( pEList == 0 ) goto limit_where_cleanup_2;
160 
161   /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
162   ** and the SELECT subtree. */
163   pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
164   if( pSelectSrc == 0 ) {
165     sqlite3ExprListDelete(pParse->db, pEList);
166     goto limit_where_cleanup_2;
167   }
168 
169   /* generate the SELECT expression tree. */
170   pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,
171                              pOrderBy,0,pLimit,pOffset);
172   if( pSelect == 0 ) return 0;
173 
174   /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
175   pWhereRowid = sqlite3PExpr(pParse, TK_ROW, 0, 0, 0);
176   if( pWhereRowid == 0 ) goto limit_where_cleanup_1;
177   pInClause = sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0);
178   if( pInClause == 0 ) goto limit_where_cleanup_1;
179 
180   pInClause->x.pSelect = pSelect;
181   pInClause->flags |= EP_xIsSelect;
182   sqlite3ExprSetHeight(pParse, pInClause);
183   return pInClause;
184 
185   /* something went wrong. clean up anything allocated. */
186 limit_where_cleanup_1:
187   sqlite3SelectDelete(pParse->db, pSelect);
188   return 0;
189 
190 limit_where_cleanup_2:
191   sqlite3ExprDelete(pParse->db, pWhere);
192   sqlite3ExprListDelete(pParse->db, pOrderBy);
193   sqlite3ExprDelete(pParse->db, pLimit);
194   sqlite3ExprDelete(pParse->db, pOffset);
195   return 0;
196 }
197 #endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) */
198 
199 /*
200 ** Generate code for a DELETE FROM statement.
201 **
202 **     DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
203 **                 \________/       \________________/
204 **                  pTabList              pWhere
205 */
206 void sqlite3DeleteFrom(
207   Parse *pParse,         /* The parser context */
208   SrcList *pTabList,     /* The table from which we should delete things */
209   Expr *pWhere           /* The WHERE clause.  May be null */
210 ){
211   Vdbe *v;               /* The virtual database engine */
212   Table *pTab;           /* The table from which records will be deleted */
213   const char *zDb;       /* Name of database holding pTab */
214   int end, addr = 0;     /* A couple addresses of generated code */
215   int i;                 /* Loop counter */
216   WhereInfo *pWInfo;     /* Information about the WHERE clause */
217   Index *pIdx;           /* For looping over indices of the table */
218   int iCur;              /* VDBE Cursor number for pTab */
219   sqlite3 *db;           /* Main database structure */
220   AuthContext sContext;  /* Authorization context */
221   int oldIdx = -1;       /* Cursor for the OLD table of AFTER triggers */
222   NameContext sNC;       /* Name context to resolve expressions in */
223   int iDb;               /* Database number */
224   int memCnt = -1;       /* Memory cell used for change counting */
225   int rcauth;            /* Value returned by authorization callback */
226 
227 #ifndef SQLITE_OMIT_TRIGGER
228   int isView;                  /* True if attempting to delete from a view */
229   Trigger *pTrigger;           /* List of table triggers, if required */
230 #endif
231   int iBeginAfterTrigger = 0;  /* Address of after trigger program */
232   int iEndAfterTrigger = 0;    /* Exit of after trigger program */
233   int iBeginBeforeTrigger = 0; /* Address of before trigger program */
234   int iEndBeforeTrigger = 0;   /* Exit of before trigger program */
235   u32 old_col_mask = 0;        /* Mask of OLD.* columns in use */
236 
237   sContext.pParse = 0;
238   db = pParse->db;
239   if( pParse->nErr || db->mallocFailed ){
240     goto delete_from_cleanup;
241   }
242   assert( pTabList->nSrc==1 );
243 
244   /* Locate the table which we want to delete.  This table has to be
245   ** put in an SrcList structure because some of the subroutines we
246   ** will be calling are designed to work with multiple tables and expect
247   ** an SrcList* parameter instead of just a Table* parameter.
248   */
249   pTab = sqlite3SrcListLookup(pParse, pTabList);
250   if( pTab==0 )  goto delete_from_cleanup;
251 
252   /* Figure out if we have any triggers and if the table being
253   ** deleted from is a view
254   */
255 #ifndef SQLITE_OMIT_TRIGGER
256   pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
257   isView = pTab->pSelect!=0;
258 #else
259 # define pTrigger 0
260 # define isView 0
261 #endif
262 #ifdef SQLITE_OMIT_VIEW
263 # undef isView
264 # define isView 0
265 #endif
266 
267   if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){
268     goto delete_from_cleanup;
269   }
270   iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
271   assert( iDb<db->nDb );
272   zDb = db->aDb[iDb].zName;
273   rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb);
274   assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
275   if( rcauth==SQLITE_DENY ){
276     goto delete_from_cleanup;
277   }
278   assert(!isView || pTrigger);
279 
280   /* If pTab is really a view, make sure it has been initialized.
281   */
282   if( sqlite3ViewGetColumnNames(pParse, pTab) ){
283     goto delete_from_cleanup;
284   }
285 
286   /* Allocate a cursor used to store the old.* data for a trigger.
287   */
288   if( pTrigger ){
289     oldIdx = pParse->nTab++;
290   }
291 
292   /* Assign  cursor number to the table and all its indices.
293   */
294   assert( pTabList->nSrc==1 );
295   iCur = pTabList->a[0].iCursor = pParse->nTab++;
296   for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
297     pParse->nTab++;
298   }
299 
300   /* Start the view context
301   */
302   if( isView ){
303     sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
304   }
305 
306   /* Begin generating code.
307   */
308   v = sqlite3GetVdbe(pParse);
309   if( v==0 ){
310     goto delete_from_cleanup;
311   }
312   if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
313   sqlite3BeginWriteOperation(pParse, (pTrigger?1:0), iDb);
314 
315   if( pTrigger ){
316     int orconf = ((pParse->trigStack)?pParse->trigStack->orconf:OE_Default);
317     int iGoto = sqlite3VdbeAddOp0(v, OP_Goto);
318     addr = sqlite3VdbeMakeLabel(v);
319 
320     iBeginBeforeTrigger = sqlite3VdbeCurrentAddr(v);
321     (void)sqlite3CodeRowTrigger(pParse, pTrigger, TK_DELETE, 0,
322         TRIGGER_BEFORE, pTab, -1, oldIdx, orconf, addr, &old_col_mask, 0);
323     iEndBeforeTrigger = sqlite3VdbeAddOp0(v, OP_Goto);
324 
325     iBeginAfterTrigger = sqlite3VdbeCurrentAddr(v);
326     (void)sqlite3CodeRowTrigger(pParse, pTrigger, TK_DELETE, 0,
327         TRIGGER_AFTER, pTab, -1, oldIdx, orconf, addr, &old_col_mask, 0);
328     iEndAfterTrigger = sqlite3VdbeAddOp0(v, OP_Goto);
329 
330     sqlite3VdbeJumpHere(v, iGoto);
331   }
332 
333   /* If we are trying to delete from a view, realize that view into
334   ** a ephemeral table.
335   */
336 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
337   if( isView ){
338     sqlite3MaterializeView(pParse, pTab, pWhere, iCur);
339   }
340 #endif
341 
342   /* Resolve the column names in the WHERE clause.
343   */
344   memset(&sNC, 0, sizeof(sNC));
345   sNC.pParse = pParse;
346   sNC.pSrcList = pTabList;
347   if( sqlite3ResolveExprNames(&sNC, pWhere) ){
348     goto delete_from_cleanup;
349   }
350 
351   /* Initialize the counter of the number of rows deleted, if
352   ** we are counting rows.
353   */
354   if( db->flags & SQLITE_CountRows ){
355     memCnt = ++pParse->nMem;
356     sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
357   }
358 
359 #ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
360   /* Special case: A DELETE without a WHERE clause deletes everything.
361   ** It is easier just to erase the whole table.  Note, however, that
362   ** this means that the row change count will be incorrect.
363   */
364   if( rcauth==SQLITE_OK && pWhere==0 && !pTrigger && !IsVirtual(pTab) ){
365     assert( !isView );
366     sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt,
367                       pTab->zName, P4_STATIC);
368     for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
369       assert( pIdx->pSchema==pTab->pSchema );
370       sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
371     }
372   }else
373 #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
374   /* The usual case: There is a WHERE clause so we have to scan through
375   ** the table and pick which records to delete.
376   */
377   {
378     int iRowid = ++pParse->nMem;    /* Used for storing rowid values. */
379     int iRowSet = ++pParse->nMem;   /* Register for rowset of rows to delete */
380     int regRowid;                   /* Actual register containing rowids */
381 
382     /* Collect rowids of every row to be deleted.
383     */
384     sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
385     pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0,WHERE_DUPLICATES_OK);
386     if( pWInfo==0 ) goto delete_from_cleanup;
387     regRowid = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, iRowid, 0);
388     sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, regRowid);
389     if( db->flags & SQLITE_CountRows ){
390       sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
391     }
392     sqlite3WhereEnd(pWInfo);
393 
394     /* Open the pseudo-table used to store OLD if there are triggers.
395     */
396     if( pTrigger ){
397       sqlite3VdbeAddOp3(v, OP_OpenPseudo, oldIdx, 0, pTab->nCol);
398     }
399 
400     /* Delete every item whose key was written to the list during the
401     ** database scan.  We have to delete items after the scan is complete
402     ** because deleting an item can change the scan order.
403     */
404     end = sqlite3VdbeMakeLabel(v);
405 
406     if( !isView ){
407       /* Open cursors for the table we are deleting from and
408       ** all its indices.
409       */
410       sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite);
411     }
412 
413     /* This is the beginning of the delete loop. If a trigger encounters
414     ** an IGNORE constraint, it jumps back to here.
415     */
416     if( pTrigger ){
417       sqlite3VdbeResolveLabel(v, addr);
418     }
419     addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, end, iRowid);
420 
421     if( pTrigger ){
422       int iData = ++pParse->nMem;   /* For storing row data of OLD table */
423 
424       /* If the record is no longer present in the table, jump to the
425       ** next iteration of the loop through the contents of the fifo.
426       */
427       sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, iRowid);
428 
429       /* Populate the OLD.* pseudo-table */
430       if( old_col_mask ){
431         sqlite3VdbeAddOp2(v, OP_RowData, iCur, iData);
432       }else{
433         sqlite3VdbeAddOp2(v, OP_Null, 0, iData);
434       }
435       sqlite3VdbeAddOp3(v, OP_Insert, oldIdx, iData, iRowid);
436 
437       /* Jump back and run the BEFORE triggers */
438       sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginBeforeTrigger);
439       sqlite3VdbeJumpHere(v, iEndBeforeTrigger);
440     }
441 
442     if( !isView ){
443       /* Delete the row */
444 #ifndef SQLITE_OMIT_VIRTUALTABLE
445       if( IsVirtual(pTab) ){
446         const char *pVtab = (const char *)pTab->pVtab;
447         sqlite3VtabMakeWritable(pParse, pTab);
448         sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iRowid, pVtab, P4_VTAB);
449       }else
450 #endif
451       {
452         sqlite3GenerateRowDelete(pParse, pTab, iCur, iRowid, pParse->nested==0);
453       }
454     }
455 
456     /* If there are row triggers, close all cursors then invoke
457     ** the AFTER triggers
458     */
459     if( pTrigger ){
460       /* Jump back and run the AFTER triggers */
461       sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginAfterTrigger);
462       sqlite3VdbeJumpHere(v, iEndAfterTrigger);
463     }
464 
465     /* End of the delete loop */
466     sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
467     sqlite3VdbeResolveLabel(v, end);
468 
469     /* Close the cursors after the loop if there are no row triggers */
470     if( !isView  && !IsVirtual(pTab) ){
471       for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
472         sqlite3VdbeAddOp2(v, OP_Close, iCur + i, pIdx->tnum);
473       }
474       sqlite3VdbeAddOp1(v, OP_Close, iCur);
475     }
476   }
477 
478   /* Update the sqlite_sequence table by storing the content of the
479   ** maximum rowid counter values recorded while inserting into
480   ** autoincrement tables.
481   */
482   if( pParse->nested==0 && pParse->trigStack==0 ){
483     sqlite3AutoincrementEnd(pParse);
484   }
485 
486   /*
487   ** Return the number of rows that were deleted. If this routine is
488   ** generating code because of a call to sqlite3NestedParse(), do not
489   ** invoke the callback function.
490   */
491   if( db->flags & SQLITE_CountRows && pParse->nested==0 && !pParse->trigStack ){
492     sqlite3VdbeAddOp2(v, OP_ResultRow, memCnt, 1);
493     sqlite3VdbeSetNumCols(v, 1);
494     sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
495   }
496 
497 delete_from_cleanup:
498   sqlite3AuthContextPop(&sContext);
499   sqlite3SrcListDelete(db, pTabList);
500   sqlite3ExprDelete(db, pWhere);
501   return;
502 }
503 
504 /*
505 ** This routine generates VDBE code that causes a single row of a
506 ** single table to be deleted.
507 **
508 ** The VDBE must be in a particular state when this routine is called.
509 ** These are the requirements:
510 **
511 **   1.  A read/write cursor pointing to pTab, the table containing the row
512 **       to be deleted, must be opened as cursor number "base".
513 **
514 **   2.  Read/write cursors for all indices of pTab must be open as
515 **       cursor number base+i for the i-th index.
516 **
517 **   3.  The record number of the row to be deleted must be stored in
518 **       memory cell iRowid.
519 **
520 ** This routine pops the top of the stack to remove the record number
521 ** and then generates code to remove both the table record and all index
522 ** entries that point to that record.
523 */
524 void sqlite3GenerateRowDelete(
525   Parse *pParse,     /* Parsing context */
526   Table *pTab,       /* Table containing the row to be deleted */
527   int iCur,          /* Cursor number for the table */
528   int iRowid,        /* Memory cell that contains the rowid to delete */
529   int count          /* Increment the row change counter */
530 ){
531   int addr;
532   Vdbe *v;
533 
534   v = pParse->pVdbe;
535   addr = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, iRowid);
536   sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, 0);
537   sqlite3VdbeAddOp2(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));
538   if( count ){
539     sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
540   }
541   sqlite3VdbeJumpHere(v, addr);
542 }
543 
544 /*
545 ** This routine generates VDBE code that causes the deletion of all
546 ** index entries associated with a single row of a single table.
547 **
548 ** The VDBE must be in a particular state when this routine is called.
549 ** These are the requirements:
550 **
551 **   1.  A read/write cursor pointing to pTab, the table containing the row
552 **       to be deleted, must be opened as cursor number "iCur".
553 **
554 **   2.  Read/write cursors for all indices of pTab must be open as
555 **       cursor number iCur+i for the i-th index.
556 **
557 **   3.  The "iCur" cursor must be pointing to the row that is to be
558 **       deleted.
559 */
560 void sqlite3GenerateRowIndexDelete(
561   Parse *pParse,     /* Parsing and code generating context */
562   Table *pTab,       /* Table containing the row to be deleted */
563   int iCur,          /* Cursor number for the table */
564   int *aRegIdx       /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
565 ){
566   int i;
567   Index *pIdx;
568   int r1;
569 
570   for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
571     if( aRegIdx!=0 && aRegIdx[i-1]==0 ) continue;
572     r1 = sqlite3GenerateIndexKey(pParse, pIdx, iCur, 0, 0);
573     sqlite3VdbeAddOp3(pParse->pVdbe, OP_IdxDelete, iCur+i, r1,pIdx->nColumn+1);
574   }
575 }
576 
577 /*
578 ** Generate code that will assemble an index key and put it in register
579 ** regOut.  The key with be for index pIdx which is an index on pTab.
580 ** iCur is the index of a cursor open on the pTab table and pointing to
581 ** the entry that needs indexing.
582 **
583 ** Return a register number which is the first in a block of
584 ** registers that holds the elements of the index key.  The
585 ** block of registers has already been deallocated by the time
586 ** this routine returns.
587 */
588 int sqlite3GenerateIndexKey(
589   Parse *pParse,     /* Parsing context */
590   Index *pIdx,       /* The index for which to generate a key */
591   int iCur,          /* Cursor number for the pIdx->pTable table */
592   int regOut,        /* Write the new index key to this register */
593   int doMakeRec      /* Run the OP_MakeRecord instruction if true */
594 ){
595   Vdbe *v = pParse->pVdbe;
596   int j;
597   Table *pTab = pIdx->pTable;
598   int regBase;
599   int nCol;
600 
601   nCol = pIdx->nColumn;
602   regBase = sqlite3GetTempRange(pParse, nCol+1);
603   sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regBase+nCol);
604   for(j=0; j<nCol; j++){
605     int idx = pIdx->aiColumn[j];
606     if( idx==pTab->iPKey ){
607       sqlite3VdbeAddOp2(v, OP_SCopy, regBase+nCol, regBase+j);
608     }else{
609       sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
610       sqlite3ColumnDefault(v, pTab, idx);
611     }
612   }
613   if( doMakeRec ){
614     sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
615     sqlite3IndexAffinityStr(v, pIdx);
616     sqlite3ExprCacheAffinityChange(pParse, regBase, nCol+1);
617   }
618   sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
619   return regBase;
620 }
621 
622 /* Make sure "isView" gets undefined in case this file becomes part of
623 ** the amalgamation - so that subsequent files do not see isView as a
624 ** macro. */
625 #undef isView
626