SQLite

    **   if eof(csr) goto end_of_scan;
    **   regChng = 0
    **   goto next_push_0;
    **
    */
    addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
    VdbeCoverage(v);
    sqlite3VdbeZeroRegister(v, regChng);
    addrNextRow = sqlite3VdbeCurrentAddr(v);

    if( nColTest>0 ){
      int endDistinctTest = sqlite3VdbeMakeLabel(v);
      int *aGotoChng;               /* Array of jump instruction addresses */
      aGotoChng = sqlite3DbMallocRaw(db, sizeof(int)*nColTest);
      if( aGotoChng==0 ) continue;

    ** The rowid for the new entry is left in register pParse->regRowid.
    ** The root page number of the new table is left in reg pParse->regRoot.
    ** The rowid and root page number values are needed by the code that
    ** sqlite3EndTable will generate.
    */
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_VIRTUALTABLE)
    if( isView || isVirtual ){
      sqlite3VdbeZeroRegister(v, reg2);
    }else
#endif
    {
      pParse->addrCrTab = sqlite3VdbeAddOp2(v, OP_CreateTable, iDb, reg2);
    }
    sqlite3OpenMasterTable(pParse, iDb);
    sqlite3VdbeAddOp2(v, OP_NewRowid, 0, reg1);

  }

  /* Initialize the counter of the number of rows deleted, if
  ** we are counting rows.
  */
  if( db->flags & SQLITE_CountRows ){
    memCnt = ++pParse->nMem;
    sqlite3VdbeZeroRegister(v, memCnt);
  }

#ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
  /* Special case: A DELETE without a WHERE clause deletes everything.
  ** It is easier just to erase the whole table. Prior to version 3.6.5,
  ** this optimization caused the row change count (the value returned by 
  ** API function sqlite3_count_changes) to be set incorrectly.  */

** Generate code that checks the left-most column of index table iCur to see if
** it contains any NULL entries.  Cause the register at regHasNull to be set
** to a non-NULL value if iCur contains no NULLs.  Cause register regHasNull
** to be set to NULL if iCur contains one or more NULL values.
*/
static void sqlite3SetHasNullFlag(Vdbe *v, int iCur, int regHasNull){
  int addr1;
  sqlite3VdbeZeroRegister(v, regHasNull);
  addr1 = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v);
  sqlite3VdbeAddOp3(v, OP_Column, iCur, 0, regHasNull);
  sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
  VdbeComment((v, "first_entry_in(%d)", iCur));
  sqlite3VdbeJumpHere(v, addr1);
}

      if( pExpr->op==TK_SELECT ){
        dest.eDest = SRT_Mem;
        dest.iSdst = dest.iSDParm;
        sqlite3VdbeAddOp2(v, OP_Null, 0, dest.iSDParm);
        VdbeComment((v, "Init subquery result"));
      }else{
        dest.eDest = SRT_Exists;
        sqlite3VdbeZeroRegister(v, dest.iSDParm);
        VdbeComment((v, "Init EXISTS result"));
      }
      sqlite3ExprDelete(pParse->db, pSel->pLimit);
      pSel->pLimit = sqlite3PExpr(pParse, TK_INTEGER, 0, 0,
                                  &sqlite3IntTokens[1]);
      pSel->iLimit = 0;
      pSel->selFlags &= ~SF_MultiValue;

      assert( TK_NOTNULL==OP_NotNull ); testcase( op==TK_NOTNULL );
      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      testcase( regFree1==0 );
      addr = sqlite3VdbeAddOp1(v, op, r1);
      VdbeCoverageIf(v, op==TK_ISNULL);
      VdbeCoverageIf(v, op==TK_NOTNULL);
      sqlite3VdbeZeroRegister(v, target);
      sqlite3VdbeJumpHere(v, addr);
      break;
    }
    case TK_AGG_FUNCTION: {
      AggInfo *pInfo = pExpr->pAggInfo;
      if( pInfo==0 ){
        assert( !ExprHasProperty(pExpr, EP_IntValue) );

    goto insert_cleanup;
  }
    
  /* Initialize the count of rows to be inserted
  */
  if( db->flags & SQLITE_CountRows ){
    regRowCount = ++pParse->nMem;
    sqlite3VdbeZeroRegister(v, regRowCount);
  }

  /* If this is not a view, open the table and and all indices */
  if( !isView ){
    int nIdx;
    nIdx = sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, 0, -1, 0,
                                      &iDataCur, &iIdxCur);

        addr = sqlite3VdbeAddOp1(v, OP_IfPos, 1);  /* Stop if out of errors */
        VdbeCoverage(v);
        sqlite3VdbeAddOp2(v, OP_Halt, 0, 0);
        sqlite3VdbeJumpHere(v, addr);
        sqlite3ExprCacheClear(pParse);
        sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenRead, 0,
                                   1, 0, &iDataCur, &iIdxCur);
        sqlite3VdbeZeroRegister(v, 7);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          sqlite3VdbeZeroRegister(v, 8+j); /* index entries counter */
        }
        pParse->nMem = MAX(pParse->nMem, 8+j);
        sqlite3VdbeAddOp2(v, OP_Rewind, iDataCur, 0); VdbeCoverage(v);
        loopTop = sqlite3VdbeAddOp2(v, OP_AddImm, 7, 1);
        /* Verify that all NOT NULL columns really are NOT NULL */
        for(j=0; j<pTab->nCol; j++){
          char *zErr;

  if( op==TK_ALL ){
    regPrev = 0;
  }else{
    int nExpr = p->pEList->nExpr;
    assert( nOrderBy>=nExpr || db->mallocFailed );
    regPrev = pParse->nMem+1;
    pParse->nMem += nExpr+1;
    sqlite3VdbeZeroRegister(v, regPrev);
    pKeyDup = sqlite3KeyInfoAlloc(db, nExpr, 1);
    if( pKeyDup ){
      assert( sqlite3KeyInfoIsWriteable(pKeyDup) );
      for(i=0; i<nExpr; i++){
        pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
        pKeyDup->aSortOrder[i] = 0;
      }

      ** is a register allocated to hold the subroutine return address
      */
      int topAddr;
      int onceAddr = 0;
      int retAddr;
      assert( pItem->addrFillSub==0 );
      pItem->regReturn = ++pParse->nMem;
      topAddr = sqlite3VdbeZeroRegister(v, pItem->regReturn);
      pItem->addrFillSub = topAddr+1;
      if( pItem->fg.isCorrelated==0 ){
        /* If the subquery is not correlated and if we are not inside of
        ** a trigger, then we only need to compute the value of the subquery
        ** once. */
        onceAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v);
        VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName));

      addrOutputRow = sqlite3VdbeMakeLabel(v);
      regReset = ++pParse->nMem;
      addrReset = sqlite3VdbeMakeLabel(v);
      iAMem = pParse->nMem + 1;
      pParse->nMem += pGroupBy->nExpr;
      iBMem = pParse->nMem + 1;
      pParse->nMem += pGroupBy->nExpr;
      sqlite3VdbeZeroRegister(v, iAbortFlag);
      VdbeComment((v, "clear abort flag"));
      sqlite3VdbeZeroRegister(v, iUseFlag);
      VdbeComment((v, "indicate accumulator empty"));
      sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1);

      /* Begin a loop that will extract all source rows in GROUP BY order.
      ** This might involve two separate loops with an OP_Sort in between, or
      ** it might be a single loop that uses an index to extract information
      ** in the right order to begin with.

    sqlite3WhereEnd(pWInfo);
  }

  /* Initialize the count of updated rows
  */
  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab ){
    regRowCount = ++pParse->nMem;
    sqlite3VdbeZeroRegister(v, regRowCount);
  }

  labelBreak = sqlite3VdbeMakeLabel(v);
  if( !isView ){
    /* 
    ** Open every index that needs updating.  Note that if any
    ** index could potentially invoke a REPLACE conflict resolution 

*/
Vdbe *sqlite3VdbeCreate(Parse*);
int sqlite3VdbeAddOp0(Vdbe*,int);
int sqlite3VdbeAddOp1(Vdbe*,int,int);
int sqlite3VdbeAddOp2(Vdbe*,int,int,int);
int sqlite3VdbeGoto(Vdbe*,int);
int sqlite3VdbeLoadString(Vdbe*,int,const char*);
int sqlite3VdbeZeroRegister(Vdbe*,int);
void sqlite3VdbeMultiLoad(Vdbe*,int,const char*,...);
int sqlite3VdbeAddOp3(Vdbe*,int,int,int,int);
int sqlite3VdbeAddOp4(Vdbe*,int,int,int,int,const char *zP4,int);
int sqlite3VdbeAddOp4Dup8(Vdbe*,int,int,int,int,const u8*,int);
int sqlite3VdbeAddOp4Int(Vdbe*,int,int,int,int,int);
#if defined(SQLITE_DEBUG) && !defined(SQLITE_TEST_REALLOC_STRESS)
  void sqlite3VdbeVerifyNoMallocRequired(Vdbe *p, int N);

/* Generate code to cause the string zStr to be loaded into
** register iDest
*/
int sqlite3VdbeLoadString(Vdbe *p, int iDest, const char *zStr){
  return sqlite3VdbeAddOp4(p, OP_String8, 0, iDest, 0, zStr, 0);
}

/* Generate code to zero a register
*/
int sqlite3VdbeZeroRegister(Vdbe *p, int iDest){
  return sqlite3VdbeAddOp3(p, OP_Integer, 0, iDest, 0);
}

/*
** Generate code that initializes multiple registers to string or integer
** constants.  The registers begin with iDest and increase consecutively.
** One register is initialized for each characgter in zTypes[].  For each
** "s" character in zTypes[], the register is a string if the argument is
** not NULL, or OP_Null if the value is a null pointer.  For each "i" character

  VdbeComment((v, "for %s", pTable->zName));

  /* Fill the automatic index with content */
  sqlite3ExprCachePush(pParse);
  pTabItem = &pWC->pWInfo->pTabList->a[pLevel->iFrom];
  if( pTabItem->fg.viaCoroutine ){
    int regYield = pTabItem->regReturn;
    addrCounter = sqlite3VdbeZeroRegister(v, 0);
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
    addrTop =  sqlite3VdbeAddOp1(v, OP_Yield, regYield);
    VdbeCoverage(v);
    VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName));
  }else{
    addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v);
  }

  /* If this is the right table of a LEFT OUTER JOIN, allocate and
  ** initialize a memory cell that records if this table matches any
  ** row of the left table of the join.
  */
  if( pLevel->iFrom>0 && (pTabItem[0].fg.jointype & JT_LEFT)!=0 ){
    pLevel->iLeftJoin = ++pParse->nMem;
    sqlite3VdbeZeroRegister(v, pLevel->iLeftJoin);
    VdbeComment((v, "init LEFT JOIN no-match flag"));
  }

  /* Special case of a FROM clause subquery implemented as a co-routine */
  if( pTabItem->fg.viaCoroutine ){
    int regYield = pTabItem->regReturn;
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);

        Index *pPk = sqlite3PrimaryKeyIndex(pTab);
        regRowset = pParse->nTab++;
        sqlite3VdbeAddOp2(v, OP_OpenEphemeral, regRowset, pPk->nKeyCol);
        sqlite3VdbeSetP4KeyInfo(pParse, pPk);
      }
      regRowid = ++pParse->nMem;
    }
    iRetInit = sqlite3VdbeZeroRegister(v, regReturn);

    /* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
    ** Then for every term xN, evaluate as the subexpression: xN AND z
    ** That way, terms in y that are factored into the disjunction will
    ** be picked up by the recursive calls to sqlite3WhereBegin() below.
    **
    ** Actually, each subexpression is converted to "xN AND w" where w is