xref: /sqlite-3.40.0/src/delete.c (revision b39187ae)
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 1.191 2008/12/23 23:56:22 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 ** Generate code that will open a table for reading.
67 */
68 void sqlite3OpenTable(
69   Parse *p,       /* Generate code into this VDBE */
70   int iCur,       /* The cursor number of the table */
71   int iDb,        /* The database index in sqlite3.aDb[] */
72   Table *pTab,    /* The table to be opened */
73   int opcode      /* OP_OpenRead or OP_OpenWrite */
74 ){
75   Vdbe *v;
76   if( IsVirtual(pTab) ) return;
77   v = sqlite3GetVdbe(p);
78   assert( opcode==OP_OpenWrite || opcode==OP_OpenRead );
79   sqlite3TableLock(p, iDb, pTab->tnum, (opcode==OP_OpenWrite)?1:0, pTab->zName);
80   sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, pTab->nCol);
81   sqlite3VdbeAddOp3(v, opcode, iCur, pTab->tnum, iDb);
82   VdbeComment((v, "%s", pTab->zName));
83 }
84 
85 
86 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
87 /*
88 ** Evaluate a view and store its result in an ephemeral table.  The
89 ** pWhere argument is an optional WHERE clause that restricts the
90 ** set of rows in the view that are to be added to the ephemeral table.
91 */
92 void sqlite3MaterializeView(
93   Parse *pParse,       /* Parsing context */
94   Table *pView,        /* View definition */
95   Expr *pWhere,        /* Optional WHERE clause to be added */
96   int iCur             /* Cursor number for ephemerial table */
97 ){
98   SelectDest dest;
99   Select *pDup;
100   sqlite3 *db = pParse->db;
101 
102   pDup = sqlite3SelectDup(db, pView->pSelect);
103   if( pWhere ){
104     SrcList *pFrom;
105     Token viewName;
106 
107     pWhere = sqlite3ExprDup(db, pWhere);
108     viewName.z = (u8*)pView->zName;
109     viewName.n = (unsigned int)sqlite3Strlen30((const char*)viewName.z);
110     pFrom = sqlite3SrcListAppendFromTerm(pParse, 0, 0, 0, &viewName, pDup, 0,0);
111     pDup = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, 0, 0, 0, 0);
112   }
113   sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
114   sqlite3Select(pParse, pDup, &dest);
115   sqlite3SelectDelete(db, pDup);
116 }
117 #endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
118 
119 #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
120 /*
121 ** Generate an expression tree to implement the WHERE, ORDER BY,
122 ** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
123 **
124 **     DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
125 **                            \__________________________/
126 **                               pLimitWhere (pInClause)
127 */
128 Expr *sqlite3LimitWhere(
129   Parse *pParse,               /* The parser context */
130   SrcList *pSrc,               /* the FROM clause -- which tables to scan */
131   Expr *pWhere,                /* The WHERE clause.  May be null */
132   ExprList *pOrderBy,          /* The ORDER BY clause.  May be null */
133   Expr *pLimit,                /* The LIMIT clause.  May be null */
134   Expr *pOffset,               /* The OFFSET clause.  May be null */
135   char *zStmtType              /* Either DELETE or UPDATE.  For error messages. */
136 ){
137   Expr *pWhereRowid = NULL;    /* WHERE rowid .. */
138   Expr *pInClause = NULL;      /* WHERE rowid IN ( select ) */
139   Expr *pSelectRowid = NULL;   /* SELECT rowid ... */
140   ExprList *pEList = NULL;     /* Expression list contaning only pSelectRowid */
141   SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
142   Select *pSelect = NULL;      /* Complete SELECT tree */
143 
144   /* Check that there isn't an ORDER BY without a LIMIT clause.
145   */
146   if( pOrderBy && (pLimit == 0) ) {
147     sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
148     pParse->parseError = 1;
149     goto limit_where_cleanup_2;
150   }
151 
152   /* We only need to generate a select expression if there
153   ** is a limit/offset term to enforce.
154   */
155   if( pLimit == 0 ) {
156     /* if pLimit is null, pOffset will always be null as well. */
157     assert( pOffset == 0 );
158     return pWhere;
159   }
160 
161   /* Generate a select expression tree to enforce the limit/offset
162   ** term for the DELETE or UPDATE statement.  For example:
163   **   DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
164   ** becomes:
165   **   DELETE FROM table_a WHERE rowid IN (
166   **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
167   **   );
168   */
169 
170   pSelectRowid = sqlite3Expr(pParse->db, TK_ROW, 0, 0, 0);
171   if( pSelectRowid == 0 ) goto limit_where_cleanup_2;
172   pEList = sqlite3ExprListAppend(pParse, 0, pSelectRowid, 0);
173   if( pEList == 0 ) goto limit_where_cleanup_2;
174 
175   /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
176   ** and the SELECT subtree. */
177   pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc);
178   if( pSelectSrc == 0 ) {
179     sqlite3ExprListDelete(pParse->db, pEList);
180     goto limit_where_cleanup_2;
181   }
182 
183   /* generate the SELECT expression tree. */
184   pSelect = sqlite3SelectNew(pParse,pEList,pSelectSrc,pWhere,0,0,pOrderBy,0,pLimit,pOffset);
185   if( pSelect == 0 ) return 0;
186 
187   /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
188   pWhereRowid = sqlite3Expr(pParse->db, TK_ROW, 0, 0, 0);
189   if( pWhereRowid == 0 ) goto limit_where_cleanup_1;
190   pInClause = sqlite3PExpr(pParse, TK_IN, pWhereRowid, 0, 0);
191   if( pInClause == 0 ) goto limit_where_cleanup_1;
192 
193   pInClause->pSelect = pSelect;
194   sqlite3ExprSetHeight(pParse, pInClause);
195   return pInClause;
196 
197   /* something went wrong. clean up anything allocated. */
198 limit_where_cleanup_1:
199   sqlite3SelectDelete(pParse->db, pSelect);
200   return 0;
201 
202 limit_where_cleanup_2:
203   sqlite3ExprDelete(pParse->db, pWhere);
204   sqlite3ExprListDelete(pParse->db, pOrderBy);
205   sqlite3ExprDelete(pParse->db, pLimit);
206   sqlite3ExprDelete(pParse->db, pOffset);
207   return 0;
208 }
209 #endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) */
210 
211 /*
212 ** Generate code for a DELETE FROM statement.
213 **
214 **     DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
215 **                 \________/       \________________/
216 **                  pTabList              pWhere
217 */
218 void sqlite3DeleteFrom(
219   Parse *pParse,         /* The parser context */
220   SrcList *pTabList,     /* The table from which we should delete things */
221   Expr *pWhere           /* The WHERE clause.  May be null */
222 ){
223   Vdbe *v;               /* The virtual database engine */
224   Table *pTab;           /* The table from which records will be deleted */
225   const char *zDb;       /* Name of database holding pTab */
226   int end, addr = 0;     /* A couple addresses of generated code */
227   int i;                 /* Loop counter */
228   WhereInfo *pWInfo;     /* Information about the WHERE clause */
229   Index *pIdx;           /* For looping over indices of the table */
230   int iCur;              /* VDBE Cursor number for pTab */
231   sqlite3 *db;           /* Main database structure */
232   AuthContext sContext;  /* Authorization context */
233   int oldIdx = -1;       /* Cursor for the OLD table of AFTER triggers */
234   NameContext sNC;       /* Name context to resolve expressions in */
235   int iDb;               /* Database number */
236   int memCnt = -1;       /* Memory cell used for change counting */
237   int rcauth;            /* Value returned by authorization callback */
238 
239 #ifndef SQLITE_OMIT_TRIGGER
240   int isView;                  /* True if attempting to delete from a view */
241   int triggers_exist = 0;      /* True if any triggers exist */
242 #endif
243   int iBeginAfterTrigger = 0;  /* Address of after trigger program */
244   int iEndAfterTrigger = 0;    /* Exit of after trigger program */
245   int iBeginBeforeTrigger = 0; /* Address of before trigger program */
246   int iEndBeforeTrigger = 0;   /* Exit of before trigger program */
247   u32 old_col_mask = 0;        /* Mask of OLD.* columns in use */
248 
249   sContext.pParse = 0;
250   db = pParse->db;
251   if( pParse->nErr || db->mallocFailed ){
252     goto delete_from_cleanup;
253   }
254   assert( pTabList->nSrc==1 );
255 
256   /* Locate the table which we want to delete.  This table has to be
257   ** put in an SrcList structure because some of the subroutines we
258   ** will be calling are designed to work with multiple tables and expect
259   ** an SrcList* parameter instead of just a Table* parameter.
260   */
261   pTab = sqlite3SrcListLookup(pParse, pTabList);
262   if( pTab==0 )  goto delete_from_cleanup;
263 
264   /* Figure out if we have any triggers and if the table being
265   ** deleted from is a view
266   */
267 #ifndef SQLITE_OMIT_TRIGGER
268   triggers_exist = sqlite3TriggersExist(pTab, TK_DELETE, 0);
269   isView = pTab->pSelect!=0;
270 #else
271 # define triggers_exist 0
272 # define isView 0
273 #endif
274 #ifdef SQLITE_OMIT_VIEW
275 # undef isView
276 # define isView 0
277 #endif
278 
279   if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){
280     goto delete_from_cleanup;
281   }
282   iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
283   assert( iDb<db->nDb );
284   zDb = db->aDb[iDb].zName;
285   rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb);
286   assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
287   if( rcauth==SQLITE_DENY ){
288     goto delete_from_cleanup;
289   }
290   assert(!isView || triggers_exist);
291 
292   /* If pTab is really a view, make sure it has been initialized.
293   */
294   if( sqlite3ViewGetColumnNames(pParse, pTab) ){
295     goto delete_from_cleanup;
296   }
297 
298   /* Allocate a cursor used to store the old.* data for a trigger.
299   */
300   if( triggers_exist ){
301     oldIdx = pParse->nTab++;
302   }
303 
304   /* Assign  cursor number to the table and all its indices.
305   */
306   assert( pTabList->nSrc==1 );
307   iCur = pTabList->a[0].iCursor = pParse->nTab++;
308   for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
309     pParse->nTab++;
310   }
311 
312   /* Start the view context
313   */
314   if( isView ){
315     sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
316   }
317 
318   /* Begin generating code.
319   */
320   v = sqlite3GetVdbe(pParse);
321   if( v==0 ){
322     goto delete_from_cleanup;
323   }
324   if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
325   sqlite3BeginWriteOperation(pParse, triggers_exist, iDb);
326 
327   if( triggers_exist ){
328     int orconf = ((pParse->trigStack)?pParse->trigStack->orconf:OE_Default);
329     int iGoto = sqlite3VdbeAddOp0(v, OP_Goto);
330     addr = sqlite3VdbeMakeLabel(v);
331 
332     iBeginBeforeTrigger = sqlite3VdbeCurrentAddr(v);
333     (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_BEFORE, pTab,
334         -1, oldIdx, orconf, addr, &old_col_mask, 0);
335     iEndBeforeTrigger = sqlite3VdbeAddOp0(v, OP_Goto);
336 
337     iBeginAfterTrigger = sqlite3VdbeCurrentAddr(v);
338     (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_AFTER, pTab, -1,
339         oldIdx, orconf, addr, &old_col_mask, 0);
340     iEndAfterTrigger = sqlite3VdbeAddOp0(v, OP_Goto);
341 
342     sqlite3VdbeJumpHere(v, iGoto);
343   }
344 
345   /* If we are trying to delete from a view, realize that view into
346   ** a ephemeral table.
347   */
348 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
349   if( isView ){
350     sqlite3MaterializeView(pParse, pTab, pWhere, iCur);
351   }
352 #endif
353 
354   /* Resolve the column names in the WHERE clause.
355   */
356   memset(&sNC, 0, sizeof(sNC));
357   sNC.pParse = pParse;
358   sNC.pSrcList = pTabList;
359   if( sqlite3ResolveExprNames(&sNC, pWhere) ){
360     goto delete_from_cleanup;
361   }
362 
363   /* Initialize the counter of the number of rows deleted, if
364   ** we are counting rows.
365   */
366   if( db->flags & SQLITE_CountRows ){
367     memCnt = ++pParse->nMem;
368     sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
369   }
370 
371 #ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
372   /* Special case: A DELETE without a WHERE clause deletes everything.
373   ** It is easier just to erase the whole table.  Note, however, that
374   ** this means that the row change count will be incorrect.
375   */
376   if( rcauth==SQLITE_OK && pWhere==0 && !triggers_exist && !IsVirtual(pTab) ){
377     assert( !isView );
378     sqlite3VdbeAddOp3(v, OP_Clear, pTab->tnum, iDb, memCnt);
379     if( !pParse->nested ){
380       sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
381     }
382     for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
383       assert( pIdx->pSchema==pTab->pSchema );
384       sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
385     }
386   }else
387 #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
388   /* The usual case: There is a WHERE clause so we have to scan through
389   ** the table and pick which records to delete.
390   */
391   {
392     int iRowid = ++pParse->nMem;    /* Used for storing rowid values. */
393     int iRowSet = ++pParse->nMem;   /* Register for rowset of rows to delete */
394 
395     /* Collect rowids of every row to be deleted.
396     */
397     sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
398     pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0,
399                                WHERE_FILL_ROWSET, iRowSet);
400     if( pWInfo==0 ) goto delete_from_cleanup;
401     if( db->flags & SQLITE_CountRows ){
402       sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
403     }
404     sqlite3WhereEnd(pWInfo);
405 
406     /* Open the pseudo-table used to store OLD if there are triggers.
407     */
408     if( triggers_exist ){
409       sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, pTab->nCol);
410       sqlite3VdbeAddOp1(v, OP_OpenPseudo, oldIdx);
411     }
412 
413     /* Delete every item whose key was written to the list during the
414     ** database scan.  We have to delete items after the scan is complete
415     ** because deleting an item can change the scan order.
416     */
417     end = sqlite3VdbeMakeLabel(v);
418 
419     if( !isView ){
420       /* Open cursors for the table we are deleting from and
421       ** all its indices.
422       */
423       sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite);
424     }
425 
426     /* This is the beginning of the delete loop. If a trigger encounters
427     ** an IGNORE constraint, it jumps back to here.
428     */
429     if( triggers_exist ){
430       sqlite3VdbeResolveLabel(v, addr);
431     }
432     addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, end, iRowid);
433 
434     if( triggers_exist ){
435       int iData = ++pParse->nMem;   /* For storing row data of OLD table */
436 
437       /* If the record is no longer present in the table, jump to the
438       ** next iteration of the loop through the contents of the fifo.
439       */
440       sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, iRowid);
441 
442       /* Populate the OLD.* pseudo-table */
443       if( old_col_mask ){
444         sqlite3VdbeAddOp2(v, OP_RowData, iCur, iData);
445       }else{
446         sqlite3VdbeAddOp2(v, OP_Null, 0, iData);
447       }
448       sqlite3VdbeAddOp3(v, OP_Insert, oldIdx, iData, iRowid);
449 
450       /* Jump back and run the BEFORE triggers */
451       sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginBeforeTrigger);
452       sqlite3VdbeJumpHere(v, iEndBeforeTrigger);
453     }
454 
455     if( !isView ){
456       /* Delete the row */
457 #ifndef SQLITE_OMIT_VIRTUALTABLE
458       if( IsVirtual(pTab) ){
459         const char *pVtab = (const char *)pTab->pVtab;
460         sqlite3VtabMakeWritable(pParse, pTab);
461         sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iRowid, pVtab, P4_VTAB);
462       }else
463 #endif
464       {
465         sqlite3GenerateRowDelete(pParse, pTab, iCur, iRowid, pParse->nested==0);
466       }
467     }
468 
469     /* If there are row triggers, close all cursors then invoke
470     ** the AFTER triggers
471     */
472     if( triggers_exist ){
473       /* Jump back and run the AFTER triggers */
474       sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginAfterTrigger);
475       sqlite3VdbeJumpHere(v, iEndAfterTrigger);
476     }
477 
478     /* End of the delete loop */
479     sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
480     sqlite3VdbeResolveLabel(v, end);
481 
482     /* Close the cursors after the loop if there are no row triggers */
483     if( !isView  && !IsVirtual(pTab) ){
484       for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
485         sqlite3VdbeAddOp2(v, OP_Close, iCur + i, pIdx->tnum);
486       }
487       sqlite3VdbeAddOp1(v, OP_Close, iCur);
488     }
489   }
490 
491   /*
492   ** Return the number of rows that were deleted. If this routine is
493   ** generating code because of a call to sqlite3NestedParse(), do not
494   ** invoke the callback function.
495   */
496   if( db->flags & SQLITE_CountRows && pParse->nested==0 && !pParse->trigStack ){
497     sqlite3VdbeAddOp2(v, OP_ResultRow, memCnt, 1);
498     sqlite3VdbeSetNumCols(v, 1);
499     sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
500   }
501 
502 delete_from_cleanup:
503   sqlite3AuthContextPop(&sContext);
504   sqlite3SrcListDelete(db, pTabList);
505   sqlite3ExprDelete(db, pWhere);
506   return;
507 }
508 
509 /*
510 ** This routine generates VDBE code that causes a single row of a
511 ** single table to be deleted.
512 **
513 ** The VDBE must be in a particular state when this routine is called.
514 ** These are the requirements:
515 **
516 **   1.  A read/write cursor pointing to pTab, the table containing the row
517 **       to be deleted, must be opened as cursor number "base".
518 **
519 **   2.  Read/write cursors for all indices of pTab must be open as
520 **       cursor number base+i for the i-th index.
521 **
522 **   3.  The record number of the row to be deleted must be stored in
523 **       memory cell iRowid.
524 **
525 ** This routine pops the top of the stack to remove the record number
526 ** and then generates code to remove both the table record and all index
527 ** entries that point to that record.
528 */
529 void sqlite3GenerateRowDelete(
530   Parse *pParse,     /* Parsing context */
531   Table *pTab,       /* Table containing the row to be deleted */
532   int iCur,          /* Cursor number for the table */
533   int iRowid,        /* Memory cell that contains the rowid to delete */
534   int count          /* Increment the row change counter */
535 ){
536   int addr;
537   Vdbe *v;
538 
539   v = pParse->pVdbe;
540   addr = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, iRowid);
541   sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, 0);
542   sqlite3VdbeAddOp2(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));
543   if( count ){
544     sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_STATIC);
545   }
546   sqlite3VdbeJumpHere(v, addr);
547 }
548 
549 /*
550 ** This routine generates VDBE code that causes the deletion of all
551 ** index entries associated with a single row of a single table.
552 **
553 ** The VDBE must be in a particular state when this routine is called.
554 ** These are the requirements:
555 **
556 **   1.  A read/write cursor pointing to pTab, the table containing the row
557 **       to be deleted, must be opened as cursor number "iCur".
558 **
559 **   2.  Read/write cursors for all indices of pTab must be open as
560 **       cursor number iCur+i for the i-th index.
561 **
562 **   3.  The "iCur" cursor must be pointing to the row that is to be
563 **       deleted.
564 */
565 void sqlite3GenerateRowIndexDelete(
566   Parse *pParse,     /* Parsing and code generating context */
567   Table *pTab,       /* Table containing the row to be deleted */
568   int iCur,          /* Cursor number for the table */
569   int *aRegIdx       /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
570 ){
571   int i;
572   Index *pIdx;
573   int r1;
574 
575   for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
576     if( aRegIdx!=0 && aRegIdx[i-1]==0 ) continue;
577     r1 = sqlite3GenerateIndexKey(pParse, pIdx, iCur, 0, 0);
578     sqlite3VdbeAddOp3(pParse->pVdbe, OP_IdxDelete, iCur+i, r1,pIdx->nColumn+1);
579   }
580 }
581 
582 /*
583 ** Generate code that will assemble an index key and put it in register
584 ** regOut.  The key with be for index pIdx which is an index on pTab.
585 ** iCur is the index of a cursor open on the pTab table and pointing to
586 ** the entry that needs indexing.
587 **
588 ** Return a register number which is the first in a block of
589 ** registers that holds the elements of the index key.  The
590 ** block of registers has already been deallocated by the time
591 ** this routine returns.
592 */
593 int sqlite3GenerateIndexKey(
594   Parse *pParse,     /* Parsing context */
595   Index *pIdx,       /* The index for which to generate a key */
596   int iCur,          /* Cursor number for the pIdx->pTable table */
597   int regOut,        /* Write the new index key to this register */
598   int doMakeRec      /* Run the OP_MakeRecord instruction if true */
599 ){
600   Vdbe *v = pParse->pVdbe;
601   int j;
602   Table *pTab = pIdx->pTable;
603   int regBase;
604   int nCol;
605 
606   nCol = pIdx->nColumn;
607   regBase = sqlite3GetTempRange(pParse, nCol+1);
608   sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regBase+nCol);
609   for(j=0; j<nCol; j++){
610     int idx = pIdx->aiColumn[j];
611     if( idx==pTab->iPKey ){
612       sqlite3VdbeAddOp2(v, OP_SCopy, regBase+nCol, regBase+j);
613     }else{
614       sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
615       sqlite3ColumnDefault(v, pTab, idx);
616     }
617   }
618   if( doMakeRec ){
619     sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
620     sqlite3IndexAffinityStr(v, pIdx);
621     sqlite3ExprCacheAffinityChange(pParse, regBase, nCol+1);
622   }
623   sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
624   return regBase;
625 }
626 
627 /* Make sure "isView" gets undefined in case this file becomes part of
628 ** the amalgamation - so that subsequent files do not see isView as a
629 ** macro. */
630 #undef isView
631