/*+
−
** 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 UPDATE statements.+
−
**+
−
** $Id: update.cpp 1282 2008-11-13 09:31:33Z LarsPson $+
−
*/+
−
#include "sqliteInt.h"+
−
+
−
#ifndef SQLITE_OMIT_VIRTUALTABLE+
−
/* Forward declaration */+
−
static void updateVirtualTable(+
−
  Parse *pParse,       /* The parsing context */+
−
  SrcList *pSrc,       /* The virtual table to be modified */+
−
  Table *pTab,         /* The virtual table */+
−
  ExprList *pChanges,  /* The columns to change in the UPDATE statement */+
−
  Expr *pRowidExpr,    /* Expression used to recompute the rowid */+
−
  int *aXRef,          /* Mapping from columns of pTab to entries in pChanges */+
−
  Expr *pWhere         /* WHERE clause of the UPDATE statement */+
−
);+
−
#endif /* SQLITE_OMIT_VIRTUALTABLE */+
−
+
−
/*+
−
** The most recently coded instruction was an OP_Column to retrieve the+
−
** i-th column of table pTab. This routine sets the P3 parameter of the +
−
** OP_Column to the default value, if any.+
−
**+
−
** The default value of a column is specified by a DEFAULT clause in the +
−
** column definition. This was either supplied by the user when the table+
−
** was created, or added later to the table definition by an ALTER TABLE+
−
** command. If the latter, then the row-records in the table btree on disk+
−
** may not contain a value for the column and the default value, taken+
−
** from the P3 parameter of the OP_Column instruction, is returned instead.+
−
** If the former, then all row-records are guaranteed to include a value+
−
** for the column and the P3 value is not required.+
−
**+
−
** Column definitions created by an ALTER TABLE command may only have +
−
** literal default values specified: a number, null or a string. (If a more+
−
** complicated default expression value was provided, it is evaluated +
−
** when the ALTER TABLE is executed and one of the literal values written+
−
** into the sqlite_master table.)+
−
**+
−
** Therefore, the P3 parameter is only required if the default value for+
−
** the column is a literal number, string or null. The sqlite3ValueFromExpr()+
−
** function is capable of transforming these types of expressions into+
−
** sqlite3_value objects.+
−
*/+
−
void sqlite3ColumnDefault(Vdbe *v, Table *pTab, int i){+
−
  if( pTab && !pTab->pSelect ){+
−
    sqlite3_value *pValue;+
−
    u8 enc = ENC(sqlite3VdbeDb(v));+
−
    Column *pCol = &pTab->aCol[i];+
−
    assert( i<pTab->nCol );+
−
    sqlite3ValueFromExpr(sqlite3VdbeDb(v), pCol->pDflt, enc, pCol->affinity, &pValue);+
−
    if( pValue ){+
−
      sqlite3VdbeChangeP3(v, -1, (const char *)pValue, P3_MEM);+
−
    }else{+
−
      VdbeComment((v, "# %s.%s", pTab->zName, pCol->zName));+
−
    }+
−
  }+
−
}+
−
+
−
/*+
−
** Process an UPDATE statement.+
−
**+
−
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;+
−
**          \_______/ \________/     \______/       \________________/+
−
*            onError   pTabList      pChanges             pWhere+
−
*/+
−
void sqlite3Update(+
−
  Parse *pParse,         /* The parser context */+
−
  SrcList *pTabList,     /* The table in which we should change things */+
−
  ExprList *pChanges,    /* Things to be changed */+
−
  Expr *pWhere,          /* The WHERE clause.  May be null */+
−
  int onError            /* How to handle constraint errors */+
−
){+
−
  int i, j;              /* Loop counters */+
−
  Table *pTab;           /* The table to be updated */+
−
  int addr = 0;          /* VDBE instruction address of the start of the loop */+
−
  WhereInfo *pWInfo;     /* Information about the WHERE clause */+
−
  Vdbe *v;               /* The virtual database engine */+
−
  Index *pIdx;           /* For looping over indices */+
−
  int nIdx;              /* Number of indices that need updating */+
−
  int nIdxTotal;         /* Total number of indices */+
−
  int iCur;              /* VDBE Cursor number of pTab */+
−
  sqlite3 *db;           /* The database structure */+
−
  Index **apIdx = 0;     /* An array of indices that need updating too */+
−
  char *aIdxUsed = 0;    /* aIdxUsed[i]==1 if the i-th index is used */+
−
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the+
−
                         ** an expression for the i-th column of the table.+
−
                         ** aXRef[i]==-1 if the i-th column is not changed. */+
−
  int chngRowid;         /* True if the record number is being changed */+
−
  Expr *pRowidExpr = 0;  /* Expression defining the new record number */+
−
  int openAll = 0;       /* True if all indices need to be opened */+
−
  AuthContext sContext;  /* The authorization context */+
−
  NameContext sNC;       /* The name-context to resolve expressions in */+
−
  int iDb;               /* Database containing the table being updated */+
−
  int memCnt = 0;        /* Memory cell used for counting rows changed */+
−
  int mem1;      /* Memory address storing the rowid for next row to update */+
−
+
−
#ifndef SQLITE_OMIT_TRIGGER+
−
  int isView;                  /* Trying to update a view */+
−
  int triggers_exist = 0;      /* True if any row triggers exist */+
−
#endif+
−
+
−
  int newIdx      = -1;  /* index of trigger "new" temp table       */+
−
  int oldIdx      = -1;  /* index of trigger "old" temp table       */+
−
+
−
  sContext.pParse = 0;+
−
  db = pParse->db;+
−
  if( pParse->nErr || db->mallocFailed ){+
−
    goto update_cleanup;+
−
  }+
−
  assert( pTabList->nSrc==1 );+
−
+
−
  /* Locate the table which we want to update. +
−
  */+
−
  pTab = sqlite3SrcListLookup(pParse, pTabList);+
−
  if( pTab==0 ) goto update_cleanup;+
−
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);+
−
+
−
  /* Figure out if we have any triggers and if the table being+
−
  ** updated is a view+
−
  */+
−
#ifndef SQLITE_OMIT_TRIGGER+
−
  triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges);+
−
  isView = pTab->pSelect!=0;+
−
#else+
−
# define triggers_exist 0+
−
# define isView 0+
−
#endif+
−
#ifdef SQLITE_OMIT_VIEW+
−
# undef isView+
−
# define isView 0+
−
#endif+
−
+
−
  if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){+
−
    goto update_cleanup;+
−
  }+
−
  if( sqlite3ViewGetColumnNames(pParse, pTab) ){+
−
    goto update_cleanup;+
−
  }+
−
  aXRef = (int*)sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );+
−
  if( aXRef==0 ) goto update_cleanup;+
−
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;+
−
+
−
  /* If there are FOR EACH ROW triggers, allocate cursors for the+
−
  ** special OLD and NEW tables+
−
  */+
−
  if( triggers_exist ){+
−
    newIdx = pParse->nTab++;+
−
    oldIdx = pParse->nTab++;+
−
  }+
−
+
−
  /* Allocate a cursors for the main database table and for all indices.+
−
  ** The index cursors might not be used, but if they are used they+
−
  ** need to occur right after the database cursor.  So go ahead and+
−
  ** allocate enough space, just in case.+
−
  */+
−
  pTabList->a[0].iCursor = iCur = pParse->nTab++;+
−
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){+
−
    pParse->nTab++;+
−
  }+
−
+
−
  /* Initialize the name-context */+
−
  memset(&sNC, 0, sizeof(sNC));+
−
  sNC.pParse = pParse;+
−
  sNC.pSrcList = pTabList;+
−
+
−
  /* Resolve the column names in all the expressions of the+
−
  ** of the UPDATE statement.  Also find the column index+
−
  ** for each column to be updated in the pChanges array.  For each+
−
  ** column to be updated, make sure we have authorization to change+
−
  ** that column.+
−
  */+
−
  chngRowid = 0;+
−
  for(i=0; i<pChanges->nExpr; i++){+
−
    if( sqlite3ExprResolveNames(&sNC, pChanges->a[i].pExpr) ){+
−
      goto update_cleanup;+
−
    }+
−
    for(j=0; j<pTab->nCol; j++){+
−
      if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){+
−
        if( j==pTab->iPKey ){+
−
          chngRowid = 1;+
−
          pRowidExpr = pChanges->a[i].pExpr;+
−
        }+
−
        aXRef[j] = i;+
−
        break;+
−
      }+
−
    }+
−
    if( j>=pTab->nCol ){+
−
      if( sqlite3IsRowid(pChanges->a[i].zName) ){+
−
        chngRowid = 1;+
−
        pRowidExpr = pChanges->a[i].pExpr;+
−
      }else{+
−
        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);+
−
        goto update_cleanup;+
−
      }+
−
    }+
−
#ifndef SQLITE_OMIT_AUTHORIZATION+
−
    {+
−
      int rc;+
−
      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,+
−
                           pTab->aCol[j].zName, db->aDb[iDb].zName);+
−
      if( rc==SQLITE_DENY ){+
−
        goto update_cleanup;+
−
      }else if( rc==SQLITE_IGNORE ){+
−
        aXRef[j] = -1;+
−
      }+
−
    }+
−
#endif+
−
  }+
−
+
−
  /* Allocate memory for the array apIdx[] and fill it with pointers to every+
−
  ** index that needs to be updated.  Indices only need updating if their+
−
  ** key includes one of the columns named in pChanges or if the record+
−
  ** number of the original table entry is changing.+
−
  */+
−
  for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){+
−
    if( chngRowid ){+
−
      i = 0;+
−
    }else {+
−
      for(i=0; i<pIdx->nColumn; i++){+
−
        if( aXRef[pIdx->aiColumn[i]]>=0 ) break;+
−
      }+
−
    }+
−
    if( i<pIdx->nColumn ) nIdx++;+
−
  }+
−
  if( nIdxTotal>0 ){+
−
    apIdx = (Index**)sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx + nIdxTotal );+
−
    if( apIdx==0 ) goto update_cleanup;+
−
    aIdxUsed = (char*)&apIdx[nIdx];+
−
  }+
−
  for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){+
−
    if( chngRowid ){+
−
      i = 0;+
−
    }else{+
−
      for(i=0; i<pIdx->nColumn; i++){+
−
        if( aXRef[pIdx->aiColumn[i]]>=0 ) break;+
−
      }+
−
    }+
−
    if( i<pIdx->nColumn ){+
−
      apIdx[nIdx++] = pIdx;+
−
      aIdxUsed[j] = 1;+
−
    }else{+
−
      aIdxUsed[j] = 0;+
−
    }+
−
  }+
−
+
−
  /* Begin generating code.+
−
  */+
−
  v = sqlite3GetVdbe(pParse);+
−
  if( v==0 ) goto update_cleanup;+
−
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);+
−
  sqlite3BeginWriteOperation(pParse, 1, iDb);+
−
  mem1 = pParse->nMem++;+
−
+
−
#ifndef SQLITE_OMIT_VIRTUALTABLE+
−
  /* Virtual tables must be handled separately */+
−
  if( IsVirtual(pTab) ){+
−
    updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,+
−
                       pWhere);+
−
    pWhere = 0;+
−
    pTabList = 0;+
−
    goto update_cleanup;+
−
  }+
−
#endif+
−
+
−
  /* Resolve the column names in all the expressions in the+
−
  ** WHERE clause.+
−
  */+
−
  if( sqlite3ExprResolveNames(&sNC, pWhere) ){+
−
    goto update_cleanup;+
−
  }+
−
+
−
  /* Start the view context+
−
  */+
−
  if( isView ){+
−
    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);+
−
  }+
−
+
−
  /* If we are trying to update a view, realize that view into+
−
  ** a ephemeral table.+
−
  */+
−
  if( isView ){+
−
    Select *pView;+
−
    pView = sqlite3SelectDup(db, pTab->pSelect);+
−
    sqlite3Select(pParse, pView, SRT_EphemTab, iCur, 0, 0, 0, 0);+
−
    sqlite3SelectDelete(pView);+
−
  }+
−
+
−
  /* Begin the database scan+
−
  */+
−
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);+
−
  if( pWInfo==0 ) goto update_cleanup;+
−
+
−
  /* Remember the rowid of every item to be updated.+
−
  */+
−
  sqlite3VdbeAddOp(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur, 0);+
−
  sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);+
−
+
−
  /* End the database scan loop.+
−
  */+
−
  sqlite3WhereEnd(pWInfo);+
−
+
−
  /* Initialize the count of updated rows+
−
  */+
−
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){+
−
    memCnt = pParse->nMem++;+
−
    sqlite3VdbeAddOp(v, OP_MemInt, 0, memCnt);+
−
  }+
−
+
−
  if( triggers_exist ){+
−
    +
−
    /* Create pseudo-tables for NEW and OLD+
−
    */+
−
    sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);+
−
    sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);+
−
    sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);+
−
    sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);+
−
+
−
    /* The top of the update loop for when there are triggers.+
−
    */+
−
    addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);+
−
    sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);+
−
    sqlite3VdbeAddOp(v, OP_MemStore, mem1, 0);+
−
    +
−
    if( !isView ){+
−
      /* Open a cursor and make it point to the record that is+
−
      ** being updated.+
−
      */+
−
      sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);+
−
    }+
−
    sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);+
−
+
−
    /* Generate the OLD table+
−
    */+
−
    sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);+
−
    sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);+
−
    sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0);+
−
+
−
    /* Generate the NEW table+
−
    */+
−
    if( chngRowid ){+
−
      sqlite3ExprCodeAndCache(pParse, pRowidExpr);+
−
    }else{+
−
      sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);+
−
    }+
−
    for(i=0; i<pTab->nCol; i++){+
−
      if( i==pTab->iPKey ){+
−
        sqlite3VdbeAddOp(v, OP_Null, 0, 0);+
−
        continue;+
−
      }+
−
      j = aXRef[i];+
−
      if( j<0 ){+
−
        sqlite3VdbeAddOp(v, OP_Column, iCur, i);+
−
        sqlite3ColumnDefault(v, pTab, i);+
−
      }else{+
−
        sqlite3ExprCodeAndCache(pParse, pChanges->a[j].pExpr);+
−
      }+
−
    }+
−
    sqlite3VdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);+
−
    if( !isView ){+
−
      sqlite3TableAffinityStr(v, pTab);+
−
    }+
−
    if( pParse->nErr ) goto update_cleanup;+
−
    sqlite3VdbeAddOp(v, OP_Insert, newIdx, 0);+
−
    if( !isView ){+
−
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);+
−
    }+
−
+
−
    /* Fire the BEFORE and INSTEAD OF triggers+
−
    */+
−
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_BEFORE, pTab,+
−
          newIdx, oldIdx, onError, addr) ){+
−
      goto update_cleanup;+
−
    }+
−
    +
−
    if( !isView ){+
−
      sqlite3VdbeAddOp(v, OP_MemLoad, mem1, 0);+
−
    }+
−
  }+
−
+
−
  if( !isView && !IsVirtual(pTab) ){+
−
    /* +
−
    ** Open every index that needs updating.  Note that if any+
−
    ** index could potentially invoke a REPLACE conflict resolution +
−
    ** action, then we need to open all indices because we might need+
−
    ** to be deleting some records.+
−
    */+
−
    sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite); +
−
    if( onError==OE_Replace ){+
−
      openAll = 1;+
−
    }else{+
−
      openAll = 0;+
−
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){+
−
        if( pIdx->onError==OE_Replace ){+
−
          openAll = 1;+
−
          break;+
−
        }+
−
      }+
−
    }+
−
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){+
−
      if( openAll || aIdxUsed[i] ){+
−
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);+
−
        sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);+
−
        sqlite3VdbeOp3(v, OP_OpenWrite, iCur+i+1, pIdx->tnum,+
−
                       (char*)pKey, P3_KEYINFO_HANDOFF);+
−
        assert( pParse->nTab>iCur+i+1 );+
−
      }+
−
    }+
−
+
−
    /* Loop over every record that needs updating.  We have to load+
−
    ** the old data for each record to be updated because some columns+
−
    ** might not change and we will need to copy the old value.+
−
    ** Also, the old data is needed to delete the old index entries.+
−
    ** So make the cursor point at the old record.+
−
    */+
−
    if( !triggers_exist ){+
−
      addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);+
−
      sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);+
−
      sqlite3VdbeAddOp(v, OP_MemStore, mem1, 0);+
−
    }+
−
    sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);+
−
    sqlite3VdbeAddOp(v, OP_MemLoad, mem1, 0);+
−
+
−
    /* If the record number will change, push the record number as it+
−
    ** will be after the update. (The old record number is currently+
−
    ** on top of the stack.)+
−
    */+
−
    if( chngRowid ){+
−
      sqlite3ExprCode(pParse, pRowidExpr);+
−
      sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);+
−
    }+
−
+
−
    /* Compute new data for this record.  +
−
    */+
−
    for(i=0; i<pTab->nCol; i++){+
−
      if( i==pTab->iPKey ){+
−
        sqlite3VdbeAddOp(v, OP_Null, 0, 0);+
−
        continue;+
−
      }+
−
      j = aXRef[i];+
−
      if( j<0 ){+
−
        sqlite3VdbeAddOp(v, OP_Column, iCur, i);+
−
        sqlite3ColumnDefault(v, pTab, i);+
−
      }else{+
−
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr);+
−
      }+
−
    }+
−
+
−
    /* Do constraint checks+
−
    */+
−
    sqlite3GenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRowid, 1,+
−
                                   onError, addr);+
−
+
−
    /* Delete the old indices for the current record.+
−
    */+
−
    sqlite3GenerateRowIndexDelete(v, pTab, iCur, aIdxUsed);+
−
+
−
    /* If changing the record number, delete the old record.+
−
    */+
−
    if( chngRowid ){+
−
      sqlite3VdbeAddOp(v, OP_Delete, iCur, 0);+
−
    }+
−
+
−
    /* Create the new index entries and the new record.+
−
    */+
−
    sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRowid, 1, -1, 0);+
−
  }+
−
+
−
  /* Increment the row counter +
−
  */+
−
  if( db->flags & SQLITE_CountRows && !pParse->trigStack){+
−
    sqlite3VdbeAddOp(v, OP_MemIncr, 1, memCnt);+
−
  }+
−
+
−
  /* If there are triggers, close all the cursors after each iteration+
−
  ** through the loop.  The fire the after triggers.+
−
  */+
−
  if( triggers_exist ){+
−
    if( !isView ){+
−
      for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){+
−
        if( openAll || aIdxUsed[i] )+
−
          sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);+
−
      }+
−
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);+
−
    }+
−
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_AFTER, pTab, +
−
          newIdx, oldIdx, onError, addr) ){+
−
      goto update_cleanup;+
−
    }+
−
  }+
−
+
−
  /* Repeat the above with the next record to be updated, until+
−
  ** all record selected by the WHERE clause have been updated.+
−
  */+
−
  sqlite3VdbeAddOp(v, OP_Goto, 0, addr);+
−
  sqlite3VdbeJumpHere(v, addr);+
−
+
−
  /* Close all tables if there were no FOR EACH ROW triggers */+
−
  if( !triggers_exist ){+
−
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){+
−
      if( openAll || aIdxUsed[i] ){+
−
        sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);+
−
      }+
−
    }+
−
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);+
−
  }else{+
−
    sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);+
−
    sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);+
−
  }+
−
+
−
  /*+
−
  ** Return the number of rows that were changed. If this routine is +
−
  ** generating code because of a call to sqlite3NestedParse(), do not+
−
  ** invoke the callback function.+
−
  */+
−
  if( db->flags & SQLITE_CountRows && !pParse->trigStack && pParse->nested==0 ){+
−
    sqlite3VdbeAddOp(v, OP_MemLoad, memCnt, 0);+
−
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);+
−
    sqlite3VdbeSetNumCols(v, 1);+
−
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", P3_STATIC);+
−
  }+
−
+
−
update_cleanup:+
−
  sqlite3AuthContextPop(&sContext);+
−
  sqlite3_free(apIdx);+
−
  sqlite3_free(aXRef);+
−
  sqlite3SrcListDelete(pTabList);+
−
  sqlite3ExprListDelete(pChanges);+
−
  sqlite3ExprDelete(pWhere);+
−
  return;+
−
}+
−
+
−
#ifndef SQLITE_OMIT_VIRTUALTABLE+
−
/*+
−
** Generate code for an UPDATE of a virtual table.+
−
**+
−
** The strategy is that we create an ephemerial table that contains+
−
** for each row to be changed:+
−
**+
−
**   (A)  The original rowid of that row.+
−
**   (B)  The revised rowid for the row. (note1)+
−
**   (C)  The content of every column in the row.+
−
**+
−
** Then we loop over this ephemeral table and for each row in+
−
** the ephermeral table call VUpdate.+
−
**+
−
** When finished, drop the ephemeral table.+
−
**+
−
** (note1) Actually, if we know in advance that (A) is always the same+
−
** as (B) we only store (A), then duplicate (A) when pulling+
−
** it out of the ephemeral table before calling VUpdate.+
−
*/+
−
static void updateVirtualTable(+
−
  Parse *pParse,       /* The parsing context */+
−
  SrcList *pSrc,       /* The virtual table to be modified */+
−
  Table *pTab,         /* The virtual table */+
−
  ExprList *pChanges,  /* The columns to change in the UPDATE statement */+
−
  Expr *pRowid,        /* Expression used to recompute the rowid */+
−
  int *aXRef,          /* Mapping from columns of pTab to entries in pChanges */+
−
  Expr *pWhere         /* WHERE clause of the UPDATE statement */+
−
){+
−
  Vdbe *v = pParse->pVdbe;  /* Virtual machine under construction */+
−
  ExprList *pEList = 0;     /* The result set of the SELECT statement */+
−
  Select *pSelect = 0;      /* The SELECT statement */+
−
  Expr *pExpr;              /* Temporary expression */+
−
  int ephemTab;             /* Table holding the result of the SELECT */+
−
  int i;                    /* Loop counter */+
−
  int addr;                 /* Address of top of loop */+
−
  sqlite3 *db = pParse->db; /* Database connection */+
−
+
−
  /* Construct the SELECT statement that will find the new values for+
−
  ** all updated rows. +
−
  */+
−
  pEList = sqlite3ExprListAppend(pParse, 0, +
−
                                 sqlite3CreateIdExpr(pParse, "_rowid_"), 0);+
−
  if( pRowid ){+
−
    pEList = sqlite3ExprListAppend(pParse, pEList,+
−
                                   sqlite3ExprDup(db, pRowid), 0);+
−
  }+
−
  assert( pTab->iPKey<0 );+
−
  for(i=0; i<pTab->nCol; i++){+
−
    if( aXRef[i]>=0 ){+
−
      pExpr = sqlite3ExprDup(db, pChanges->a[aXRef[i]].pExpr);+
−
    }else{+
−
      pExpr = sqlite3CreateIdExpr(pParse, pTab->aCol[i].zName);+
−
    }+
−
    pEList = sqlite3ExprListAppend(pParse, pEList, pExpr, 0);+
−
  }+
−
  pSelect = sqlite3SelectNew(pParse, pEList, pSrc, pWhere, 0, 0, 0, 0, 0, 0);+
−
  +
−
  /* Create the ephemeral table into which the update results will+
−
  ** be stored.+
−
  */+
−
  assert( v );+
−
  ephemTab = pParse->nTab++;+
−
  sqlite3VdbeAddOp(v, OP_OpenEphemeral, ephemTab, pTab->nCol+1+(pRowid!=0));+
−
+
−
  /* fill the ephemeral table +
−
  */+
−
  sqlite3Select(pParse, pSelect, SRT_Table, ephemTab, 0, 0, 0, 0);+
−
+
−
  /*+
−
  ** Generate code to scan the ephemeral table and call VDelete and+
−
  ** VInsert+
−
  */+
−
  sqlite3VdbeAddOp(v, OP_Rewind, ephemTab, 0);+
−
  addr = sqlite3VdbeCurrentAddr(v);+
−
  sqlite3VdbeAddOp(v, OP_Column,  ephemTab, 0);+
−
  if( pRowid ){+
−
    sqlite3VdbeAddOp(v, OP_Column, ephemTab, 1);+
−
  }else{+
−
    sqlite3VdbeAddOp(v, OP_Dup, 0, 0);+
−
  }+
−
  for(i=0; i<pTab->nCol; i++){+
−
    sqlite3VdbeAddOp(v, OP_Column, ephemTab, i+1+(pRowid!=0));+
−
  }+
−
  pParse->pVirtualLock = pTab;+
−
  sqlite3VdbeOp3(v, OP_VUpdate, 0, pTab->nCol+2, +
−
                     (const char*)pTab->pVtab, P3_VTAB);+
−
  sqlite3VdbeAddOp(v, OP_Next, ephemTab, addr);+
−
  sqlite3VdbeJumpHere(v, addr-1);+
−
  sqlite3VdbeAddOp(v, OP_Close, ephemTab, 0);+
−
+
−
  /* Cleanup */+
−
  sqlite3SelectDelete(pSelect);  +
−
}+
−
#endif /* SQLITE_OMIT_VIRTUALTABLE */+
−