/* Figure out how many bytes of space are required to store explicitly
  ** specified collation sequence names.
  */
  for(i=0; i<pList->nExpr; i++){
    Expr *pExpr = pList->a[i].pExpr;
    if( pExpr ){
      CollSeq *pColl = pExpr->pColl;
      /* Either pColl!=0 or there was an OOM failure.  But if an OOM
      ** failure we have quit before reaching this point. */
      if( ALWAYS(pColl) ){
        nExtra += (1 + sqlite3Strlen30(pColl->zName));
      }
    }
  }

  /* 
  ** Allocate the index structure. 
................................................................................
  ** same column more than once cannot be an error because that would 
  ** break backwards compatibility - it needs to be a warning.
  */
  for(i=0, pListItem=pList->a; i<pList->nExpr; i++, pListItem++){
    const char *zColName = pListItem->zName;
    Column *pTabCol;
    int requestedSortOrder;

    char *zColl;                   /* Collation sequence name */

    for(j=0, pTabCol=pTab->aCol; j<pTab->nCol; j++, pTabCol++){
      if( sqlite3StrICmp(zColName, pTabCol->zName)==0 ) break;
    }
    if( j>=pTab->nCol ){
      sqlite3ErrorMsg(pParse, "table %s has no column named %s",
        pTab->zName, zColName);
      pParse->checkSchema = 1;
      goto exit_create_index;
    }
    pIndex->aiColumn[i] = j;
    /* Justification of the ALWAYS(pListItem->pExpr->pColl):  Because of
    ** the way the "idxlist" non-terminal is constructed by the parser,
    ** if pListItem->pExpr is not null then either pListItem->pExpr->pColl
    ** must exist or else there must have been an OOM error.  But if there
    ** was an OOM error, we would never reach this point. */
    if( pListItem->pExpr && ALWAYS(pListItem->pExpr->pColl) ){


      int nColl;
      zColl = pListItem->pExpr->pColl->zName;
      nColl = sqlite3Strlen30(zColl) + 1;
      assert( nExtra>=nColl );
      memcpy(zExtra, zColl, nColl);
      zColl = zExtra;
      zExtra += nColl;
      nExtra -= nColl;
    }else{

  /* Figure out how many bytes of space are required to store explicitly
  ** specified collation sequence names.
  */
  for(i=0; i<pList->nExpr; i++){
    Expr *pExpr = pList->a[i].pExpr;
    if( pExpr ){
      CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr);
      if( pColl ){


        nExtra += (1 + sqlite3Strlen30(pColl->zName));
      }
    }
  }

  /* 
  ** Allocate the index structure. 
................................................................................
  ** same column more than once cannot be an error because that would 
  ** break backwards compatibility - it needs to be a warning.
  */
  for(i=0, pListItem=pList->a; i<pList->nExpr; i++, pListItem++){
    const char *zColName = pListItem->zName;
    Column *pTabCol;
    int requestedSortOrder;
    CollSeq *pColl;                /* Collating sequence */
    char *zColl;                   /* Collation sequence name */

    for(j=0, pTabCol=pTab->aCol; j<pTab->nCol; j++, pTabCol++){
      if( sqlite3StrICmp(zColName, pTabCol->zName)==0 ) break;
    }
    if( j>=pTab->nCol ){
      sqlite3ErrorMsg(pParse, "table %s has no column named %s",
        pTab->zName, zColName);
      pParse->checkSchema = 1;
      goto exit_create_index;
    }
    pIndex->aiColumn[i] = j;





    if( pListItem->pExpr
     && (pColl = sqlite3ExprCollSeq(pParse, pListItem->pExpr))!=0
    ){
      int nColl;
      zColl = pColl->zName;
      nColl = sqlite3Strlen30(zColl) + 1;
      assert( nExtra>=nColl );
      memcpy(zExtra, zColl, nColl);
      zColl = zExtra;
      zExtra += nColl;
      nExtra -= nColl;
    }else{

    if( j<0 ) return SQLITE_AFF_INTEGER;
    assert( pExpr->pTab && j<pExpr->pTab->nCol );
    return pExpr->pTab->aCol[j].affinity;
  }
  return pExpr->affinity;
}

/*
** Set the explicit collating sequence for an expression to the
** collating sequence supplied in the second argument.
*/
Expr *sqlite3ExprSetColl(Expr *pExpr, CollSeq *pColl){
  if( pExpr && pColl ){
    pExpr->pColl = pColl;
    pExpr->flags |= EP_ExpCollate;
  }
  return pExpr;
}

/*
** Set the collating sequence for expression pExpr to be the collating
** sequence named by pToken.   Return a pointer to the revised expression.
** The collating sequence is marked as "explicit" using the EP_ExpCollate
** flag.  An explicit collating sequence will override implicit
** collating sequences.

*/
Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr *pExpr, Token *pCollName){
  char *zColl = 0;            /* Dequoted name of collation sequence */
  CollSeq *pColl;
  sqlite3 *db = pParse->db;
  zColl = sqlite3NameFromToken(db, pCollName);
  pColl = sqlite3LocateCollSeq(pParse, zColl);
  sqlite3ExprSetColl(pExpr, pColl);
  sqlite3DbFree(db, zColl);





  return pExpr;
}

/*
** Return the default collation sequence for the expression pExpr. If
** there is no default collation type, return 0.





*/
CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){

  CollSeq *pColl = 0;
  Expr *p = pExpr;
  while( p ){
    int op;

    pColl = p->pColl;




    if( pColl ) break;
    op = p->op;

    if( p->pTab!=0 && (

        op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_REGISTER || op==TK_TRIGGER
    )){
      /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
      ** a TK_COLUMN but was previously evaluated and cached in a register */
      const char *zColl;
      int j = p->iColumn;
      if( j>=0 ){
        sqlite3 *db = pParse->db;
        zColl = p->pTab->aCol[j].zColl;
        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
        pExpr->pColl = pColl;
      }
      break;
    }
    if( op!=TK_CAST && op!=TK_UPLUS ){






      break;
    }





    p = p->pLeft;


  }
  if( sqlite3CheckCollSeq(pParse, pColl) ){ 
    pColl = 0;
  }
  return pColl;
}

................................................................................
CollSeq *sqlite3BinaryCompareCollSeq(
  Parse *pParse, 
  Expr *pLeft, 
  Expr *pRight
){
  CollSeq *pColl;
  assert( pLeft );
  if( pLeft->flags & EP_ExpCollate ){
    assert( pLeft->pColl );
    pColl = pLeft->pColl;
  }else if( pRight && pRight->flags & EP_ExpCollate ){
    assert( pRight->pColl );
    pColl = pRight->pColl;

  }else{
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
    if( !pColl ){
      pColl = sqlite3ExprCollSeq(pParse, pRight);
    }
  }
  return pColl;
................................................................................
  if( pRoot==0 ){
    assert( db->mallocFailed );
    sqlite3ExprDelete(db, pLeft);
    sqlite3ExprDelete(db, pRight);
  }else{
    if( pRight ){
      pRoot->pRight = pRight;
      if( pRight->flags & EP_ExpCollate ){
        pRoot->flags |= EP_ExpCollate;
        pRoot->pColl = pRight->pColl;
      }
    }
    if( pLeft ){
      pRoot->pLeft = pLeft;
      if( pLeft->flags & EP_ExpCollate ){
        pRoot->flags |= EP_ExpCollate;
        pRoot->pColl = pLeft->pColl;
      }
    }
    exprSetHeight(pRoot);
  }
}

/*
** Allocate a Expr node which joins as many as two subtrees.
................................................................................
  if( 0==(flags&EXPRDUP_REDUCE) ){
    nSize = EXPR_FULLSIZE;
  }else{
    assert( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) );
    assert( !ExprHasProperty(p, EP_FromJoin) ); 
    assert( (p->flags2 & EP2_MallocedToken)==0 );
    assert( (p->flags2 & EP2_Irreducible)==0 );
    if( p->pLeft || p->pRight || p->pColl || p->x.pList ){
      nSize = EXPR_REDUCEDSIZE | EP_Reduced;
    }else{
      nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
    }
  }
  return nSize;
}
................................................................................
      testcase( regFree2==0 );
      codeCompare(pParse, pLeft, pRight, OP_Le, r1, r2, r4, SQLITE_STOREP2);
      sqlite3VdbeAddOp3(v, OP_And, r3, r4, target);
      sqlite3ReleaseTempReg(pParse, r3);
      sqlite3ReleaseTempReg(pParse, r4);
      break;
    }

    case TK_UPLUS: {
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
      break;
    }

    case TK_TRIGGER: {
      /* If the opcode is TK_TRIGGER, then the expression is a reference
................................................................................
  }
  assert( !ExprHasAnyProperty(pA, EP_TokenOnly|EP_Reduced) );
  assert( !ExprHasAnyProperty(pB, EP_TokenOnly|EP_Reduced) );
  if( ExprHasProperty(pA, EP_xIsSelect) || ExprHasProperty(pB, EP_xIsSelect) ){
    return 2;
  }
  if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 2;
  if( pA->op!=pB->op ) return 2;








  if( sqlite3ExprCompare(pA->pLeft, pB->pLeft) ) return 2;
  if( sqlite3ExprCompare(pA->pRight, pB->pRight) ) return 2;
  if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList) ) return 2;
  if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 2;
  if( ExprHasProperty(pA, EP_IntValue) ){
    if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){
      return 2;
    }
  }else if( pA->op!=TK_COLUMN && ALWAYS(pA->op!=TK_AGG_COLUMN) && pA->u.zToken){
    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 2;
    if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
      return 2;
    }
  }
  if( (pA->flags & EP_ExpCollate)!=(pB->flags & EP_ExpCollate) ) return 1;
  if( (pA->flags & EP_ExpCollate)!=0 && pA->pColl!=pB->pColl ) return 2;
  return 0;
}

/*
** Compare two ExprList objects.  Return 0 if they are identical and 
** non-zero if they differ in any way.
**

    if( j<0 ) return SQLITE_AFF_INTEGER;
    assert( pExpr->pTab && j<pExpr->pTab->nCol );
    return pExpr->pTab->aCol[j].affinity;
  }
  return pExpr->affinity;
}

/*












** Set the collating sequence for expression pExpr to be the collating
** sequence named by pToken.   Return a pointer to a new Expr node that



** implements the COLLATE operator.
*/
Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr *pExpr, Token *pCollName){







  Expr *pNew = sqlite3ExprAlloc(pParse->db, TK_COLLATE, pCollName, 1);
  if( pNew ){
    pNew->pLeft = pExpr;
    pNew->flags |= EP_Collate;
  }
  return pNew;
}

/*
** Return the collation sequence for the expression pExpr. If
** there is no defined collating sequence, return NULL.
**
** The collating sequence might be determined by a COLLATE operator
** or by the presence of a column with a defined collating sequence.
** COLLATE operators take first precedence.  Left operands take
** precedence over right operands.
*/
CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr){
  sqlite3 *db = pParse->db;
  CollSeq *pColl = 0;
  Expr *p = pExpr;
  while( p && pColl==0 ){
    int op = p->op;
    if( op==TK_CAST || op==TK_UPLUS ){
      p = p->pLeft;
      continue;
    }
    if( op==TK_COLLATE ){
      pColl = sqlite3FindCollSeq(db, ENC(db), p->u.zToken, 0);
      break;

    }
    if( p->pTab!=0
     && (op==TK_AGG_COLUMN || op==TK_COLUMN
          || op==TK_REGISTER || op==TK_TRIGGER)
    ){
      /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
      ** a TK_COLUMN but was previously evaluated and cached in a register */

      int j = p->iColumn;
      if( j>=0 ){

        const char *zColl = p->pTab->aCol[j].zColl;
        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);

      }
      break;
    }
    if( p->flags & EP_Collate ){
      if( p->pLeft->flags & EP_Collate ){
        p = p->pLeft;
      }else{
        p = p->pRight;
      }
    }else{
      break;
    }
#if 0
    else if( p->flags & EP_TokenOnly ){
      break;
    }else{
      pColl = sqlite3ExprCollSeq(pParse, p->pLeft);
      p = p->pRight;
    }
#endif
  }
  if( sqlite3CheckCollSeq(pParse, pColl) ){ 
    pColl = 0;
  }
  return pColl;
}

................................................................................
CollSeq *sqlite3BinaryCompareCollSeq(
  Parse *pParse, 
  Expr *pLeft, 
  Expr *pRight
){
  CollSeq *pColl;
  assert( pLeft );
  if( pLeft->flags & EP_Collate ){
    pColl = sqlite3ExprCollSeq(pParse, pLeft);

  }else if( pRight && (pRight->flags & EP_Collate)!=0 ){


    pColl = sqlite3ExprCollSeq(pParse, pRight);
  }else{
    pColl = sqlite3ExprCollSeq(pParse, pLeft);
    if( !pColl ){
      pColl = sqlite3ExprCollSeq(pParse, pRight);
    }
  }
  return pColl;
................................................................................
  if( pRoot==0 ){
    assert( db->mallocFailed );
    sqlite3ExprDelete(db, pLeft);
    sqlite3ExprDelete(db, pRight);
  }else{
    if( pRight ){
      pRoot->pRight = pRight;

      pRoot->flags |= EP_Collate & pRight->flags;


    }
    if( pLeft ){
      pRoot->pLeft = pLeft;

      pRoot->flags |= EP_Collate & pLeft->flags;


    }
    exprSetHeight(pRoot);
  }
}

/*
** Allocate a Expr node which joins as many as two subtrees.
................................................................................
  if( 0==(flags&EXPRDUP_REDUCE) ){
    nSize = EXPR_FULLSIZE;
  }else{
    assert( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) );
    assert( !ExprHasProperty(p, EP_FromJoin) ); 
    assert( (p->flags2 & EP2_MallocedToken)==0 );
    assert( (p->flags2 & EP2_Irreducible)==0 );
    if( p->pLeft || p->pRight || p->x.pList ){
      nSize = EXPR_REDUCEDSIZE | EP_Reduced;
    }else{
      nSize = EXPR_TOKENONLYSIZE | EP_TokenOnly;
    }
  }
  return nSize;
}
................................................................................
      testcase( regFree2==0 );
      codeCompare(pParse, pLeft, pRight, OP_Le, r1, r2, r4, SQLITE_STOREP2);
      sqlite3VdbeAddOp3(v, OP_And, r3, r4, target);
      sqlite3ReleaseTempReg(pParse, r3);
      sqlite3ReleaseTempReg(pParse, r4);
      break;
    }
    case TK_COLLATE: 
    case TK_UPLUS: {
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
      break;
    }

    case TK_TRIGGER: {
      /* If the opcode is TK_TRIGGER, then the expression is a reference
................................................................................
  }
  assert( !ExprHasAnyProperty(pA, EP_TokenOnly|EP_Reduced) );
  assert( !ExprHasAnyProperty(pB, EP_TokenOnly|EP_Reduced) );
  if( ExprHasProperty(pA, EP_xIsSelect) || ExprHasProperty(pB, EP_xIsSelect) ){
    return 2;
  }
  if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 2;
  if( pA->op!=pB->op ){
    if( pA->op==TK_COLLATE && sqlite3ExprCompare(pA->pLeft, pB)<2 ){
      return 1;
    }
    if( pB->op==TK_COLLATE && sqlite3ExprCompare(pA, pB->pLeft)<2 ){
      return 1;
    }
    return 2;
  }
  if( sqlite3ExprCompare(pA->pLeft, pB->pLeft) ) return 2;
  if( sqlite3ExprCompare(pA->pRight, pB->pRight) ) return 2;
  if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList) ) return 2;
  if( pA->iTable!=pB->iTable || pA->iColumn!=pB->iColumn ) return 2;
  if( ExprHasProperty(pA, EP_IntValue) ){
    if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){
      return 2;
    }
  }else if( pA->op!=TK_COLUMN && ALWAYS(pA->op!=TK_AGG_COLUMN) && pA->u.zToken){
    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 2;
    if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
      return pA->op==TK_COLLATE ? 1 : 2;
    }
  }


  return 0;
}

/*
** Compare two ExprList objects.  Return 0 if they are identical and 
** non-zero if they differ in any way.
**

      if( pIdx ){
        Column *pCol;
        iCol = pIdx->aiColumn[i];
        pCol = &pTab->aCol[iCol];
        if( pTab->iPKey==iCol ) iCol = -1;
        pLeft->iTable = regData+iCol+1;
        pLeft->affinity = pCol->affinity;
        pLeft->pColl = sqlite3LocateCollSeq(pParse, pCol->zColl);
      }else{
        pLeft->iTable = regData;
        pLeft->affinity = SQLITE_AFF_INTEGER;
      }
    }
    iCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
    assert( iCol>=0 );

      if( pIdx ){
        Column *pCol;
        iCol = pIdx->aiColumn[i];
        pCol = &pTab->aCol[iCol];
        if( pTab->iPKey==iCol ) iCol = -1;
        pLeft->iTable = regData+iCol+1;
        pLeft->affinity = pCol->affinity;
        // fix me.  pLeft->pColl = sqlite3LocateCollSeq(pParse, pCol->zColl);
      }else{
        pLeft->iTable = regData;
        pLeft->affinity = SQLITE_AFF_INTEGER;
      }
    }
    iCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
    assert( iCol>=0 );

    pDup = sqlite3ExprDup(db, pOrig, 0);
    pOrig->u.zToken = zToken;
    if( pDup==0 ) return;
    assert( (pDup->flags & (EP_Reduced|EP_TokenOnly))==0 );
    pDup->flags2 |= EP2_MallocedToken;
    pDup->u.zToken = sqlite3DbStrDup(db, zToken);
  }
  if( pExpr->flags & EP_ExpCollate ){
    pDup->pColl = pExpr->pColl;
    pDup->flags |= EP_ExpCollate;
  }

  /* Before calling sqlite3ExprDelete(), set the EP_Static flag. This 
  ** prevents ExprDelete() from deleting the Expr structure itself,
  ** allowing it to be repopulated by the memcpy() on the following line.
  */
  ExprSetProperty(pExpr, EP_Static);
  sqlite3ExprDelete(db, pExpr);
................................................................................
            assert(pDup);
            iCol = resolveOrderByTermToExprList(pParse, pSelect, pDup);
          }
          sqlite3ExprDelete(db, pDup);
        }
      }
      if( iCol>0 ){
        CollSeq *pColl = pE->pColl;
        int flags = pE->flags & EP_ExpCollate;
        sqlite3ExprDelete(db, pE);
        pItem->pExpr = pE = sqlite3Expr(db, TK_INTEGER, 0);
        if( pE==0 ) return 1;
        pE->pColl = pColl;
        pE->flags |= EP_IntValue | flags;
        pE->u.iValue = iCol;
        pItem->iOrderByCol = (u16)iCol;
        pItem->done = 1;
      }else{
        moreToDo = 1;
      }
    }

    pDup = sqlite3ExprDup(db, pOrig, 0);
    pOrig->u.zToken = zToken;
    if( pDup==0 ) return;
    assert( (pDup->flags & (EP_Reduced|EP_TokenOnly))==0 );
    pDup->flags2 |= EP2_MallocedToken;
    pDup->u.zToken = sqlite3DbStrDup(db, zToken);
  }





  /* Before calling sqlite3ExprDelete(), set the EP_Static flag. This 
  ** prevents ExprDelete() from deleting the Expr structure itself,
  ** allowing it to be repopulated by the memcpy() on the following line.
  */
  ExprSetProperty(pExpr, EP_Static);
  sqlite3ExprDelete(db, pExpr);
................................................................................
            assert(pDup);
            iCol = resolveOrderByTermToExprList(pParse, pSelect, pDup);
          }
          sqlite3ExprDelete(db, pDup);
        }
      }
      if( iCol>0 ){


        sqlite3ExprDelete(db, pE);
        pItem->pExpr = pE = sqlite3Expr(db, TK_INTEGER, 0);
        if( pE==0 ) return 1;

        pE->flags |= EP_IntValue;
        pE->u.iValue = iCol;
        pItem->iOrderByCol = (u16)iCol;
        pItem->done = 1;
      }else{
        moreToDo = 1;
      }
    }

    if( pKeyMerge ){
      pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy];
      pKeyMerge->nField = (u16)nOrderBy;
      pKeyMerge->enc = ENC(db);
      for(i=0; i<nOrderBy; i++){
        CollSeq *pColl;
        Expr *pTerm = pOrderBy->a[i].pExpr;
        if( pTerm->flags & EP_ExpCollate ){
          pColl = pTerm->pColl;
        }else{
          pColl = multiSelectCollSeq(pParse, p, aPermute[i]);
          pTerm->flags |= EP_ExpCollate;
          pTerm->pColl = pColl;
        }
        pKeyMerge->aColl[i] = pColl;
        pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder;
      }
    }
  }else{
    pKeyMerge = 0;
................................................................................
    if( pExpr->iColumn<0 ){
      pExpr->op = TK_NULL;
    }else{
      Expr *pNew;
      assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
      assert( pExpr->pLeft==0 && pExpr->pRight==0 );
      pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0);
      if( pNew && pExpr->pColl ){
        pNew->pColl = pExpr->pColl;
      }
      sqlite3ExprDelete(db, pExpr);
      pExpr = pNew;
    }
  }else{
    pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList);
    pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList);
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){

    if( pKeyMerge ){
      pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy];
      pKeyMerge->nField = (u16)nOrderBy;
      pKeyMerge->enc = ENC(db);
      for(i=0; i<nOrderBy; i++){
        CollSeq *pColl;
        Expr *pTerm = pOrderBy->a[i].pExpr;
        if( pTerm->flags & EP_Collate ){
          pColl = sqlite3ExprCollSeq(pParse, pTerm);
        }else{
          pColl = multiSelectCollSeq(pParse, p, aPermute[i]);


        }
        pKeyMerge->aColl[i] = pColl;
        pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder;
      }
    }
  }else{
    pKeyMerge = 0;
................................................................................
    if( pExpr->iColumn<0 ){
      pExpr->op = TK_NULL;
    }else{
      Expr *pNew;
      assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
      assert( pExpr->pLeft==0 && pExpr->pRight==0 );
      pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0);



      sqlite3ExprDelete(db, pExpr);
      pExpr = pNew;
    }
  }else{
    pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList);
    pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList);
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){

  Expr *pLeft;           /* Left subnode */
  Expr *pRight;          /* Right subnode */
  union {
    ExprList *pList;     /* Function arguments or in "<expr> IN (<expr-list)" */
    Select *pSelect;     /* Used for sub-selects and "<expr> IN (<select>)" */
  } x;
  CollSeq *pColl;        /* The collation type of the column or 0 */

  /* If the EP_Reduced flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction.
  *********************************************************************/

#if SQLITE_MAX_EXPR_DEPTH>0
................................................................................
#define EP_Agg        0x0002  /* Contains one or more aggregate functions */
#define EP_Resolved   0x0004  /* IDs have been resolved to COLUMNs */
#define EP_Error      0x0008  /* Expression contains one or more errors */
#define EP_Distinct   0x0010  /* Aggregate function with DISTINCT keyword */
#define EP_VarSelect  0x0020  /* pSelect is correlated, not constant */
#define EP_DblQuoted  0x0040  /* token.z was originally in "..." */
#define EP_InfixFunc  0x0080  /* True for an infix function: LIKE, GLOB, etc */
#define EP_ExpCollate 0x0100  /* Collating sequence specified explicitly */
#define EP_FixedDest  0x0200  /* Result needed in a specific register */
#define EP_IntValue   0x0400  /* Integer value contained in u.iValue */
#define EP_xIsSelect  0x0800  /* x.pSelect is valid (otherwise x.pList is) */
#define EP_Hint       0x1000  /* Not used */
#define EP_Reduced    0x2000  /* Expr struct is EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly  0x4000  /* Expr struct is EXPR_TOKENONLYSIZE bytes only */
#define EP_Static     0x8000  /* Held in memory not obtained from malloc() */
................................................................................
u8 sqlite3HexToInt(int h);
int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
const char *sqlite3ErrStr(int);
int sqlite3ReadSchema(Parse *pParse);
CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
Expr *sqlite3ExprSetColl(Expr*, CollSeq*);
Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr*, Token*);
int sqlite3CheckCollSeq(Parse *, CollSeq *);
int sqlite3CheckObjectName(Parse *, const char *);
void sqlite3VdbeSetChanges(sqlite3 *, int);
int sqlite3AddInt64(i64*,i64);
int sqlite3SubInt64(i64*,i64);
int sqlite3MulInt64(i64*,i64);

  Expr *pLeft;           /* Left subnode */
  Expr *pRight;          /* Right subnode */
  union {
    ExprList *pList;     /* Function arguments or in "<expr> IN (<expr-list)" */
    Select *pSelect;     /* Used for sub-selects and "<expr> IN (<select>)" */
  } x;


  /* If the EP_Reduced flag is set in the Expr.flags mask, then no
  ** space is allocated for the fields below this point. An attempt to
  ** access them will result in a segfault or malfunction.
  *********************************************************************/

#if SQLITE_MAX_EXPR_DEPTH>0
................................................................................
#define EP_Agg        0x0002  /* Contains one or more aggregate functions */
#define EP_Resolved   0x0004  /* IDs have been resolved to COLUMNs */
#define EP_Error      0x0008  /* Expression contains one or more errors */
#define EP_Distinct   0x0010  /* Aggregate function with DISTINCT keyword */
#define EP_VarSelect  0x0020  /* pSelect is correlated, not constant */
#define EP_DblQuoted  0x0040  /* token.z was originally in "..." */
#define EP_InfixFunc  0x0080  /* True for an infix function: LIKE, GLOB, etc */
#define EP_Collate    0x0100  /* Tree contains a TK_COLLATE opeartor */
#define EP_FixedDest  0x0200  /* Result needed in a specific register */
#define EP_IntValue   0x0400  /* Integer value contained in u.iValue */
#define EP_xIsSelect  0x0800  /* x.pSelect is valid (otherwise x.pList is) */
#define EP_Hint       0x1000  /* Not used */
#define EP_Reduced    0x2000  /* Expr struct is EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly  0x4000  /* Expr struct is EXPR_TOKENONLYSIZE bytes only */
#define EP_Static     0x8000  /* Held in memory not obtained from malloc() */
................................................................................
u8 sqlite3HexToInt(int h);
int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
const char *sqlite3ErrStr(int);
int sqlite3ReadSchema(Parse *pParse);
CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);

Expr *sqlite3ExprSetCollByToken(Parse *pParse, Expr*, Token*);
int sqlite3CheckCollSeq(Parse *, CollSeq *);
int sqlite3CheckObjectName(Parse *, const char *);
void sqlite3VdbeSetChanges(sqlite3 *, int);
int sqlite3AddInt64(i64*,i64);
int sqlite3SubInt64(i64*,i64);
int sqlite3MulInt64(i64*,i64);

*/
#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}

/*
** Commute a comparison operator.  Expressions of the form "X op Y"
** are converted into "Y op X".
**
** If a collation sequence is associated with either the left or right

** side of the comparison, it remains associated with the same side after
** the commutation. So "Y collate NOCASE op X" becomes 
** "X collate NOCASE op Y". This is because any collation sequence on
** the left hand side of a comparison overrides any collation sequence 
** attached to the right. For the same reason the EP_ExpCollate flag
** is not commuted.
*/
static void exprCommute(Parse *pParse, Expr *pExpr){
  u16 expRight = (pExpr->pRight->flags & EP_ExpCollate);
  u16 expLeft = (pExpr->pLeft->flags & EP_ExpCollate);
  assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
  pExpr->pRight->pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight);





  pExpr->pLeft->pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft);
  SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
  pExpr->pRight->flags = (pExpr->pRight->flags & ~EP_ExpCollate) | expLeft;



  pExpr->pLeft->flags = (pExpr->pLeft->flags & ~EP_ExpCollate) | expRight;


  SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
  if( pExpr->op>=TK_GT ){
    assert( TK_LT==TK_GT+2 );
    assert( TK_GE==TK_LE+2 );
    assert( TK_GT>TK_EQ );
    assert( TK_GT<TK_LE );
    assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
................................................................................
  ){
    Expr *pLeft;       /* LHS of LIKE/GLOB operator */
    Expr *pStr2;       /* Copy of pStr1 - RHS of LIKE/GLOB operator */
    Expr *pNewExpr1;
    Expr *pNewExpr2;
    int idxNew1;
    int idxNew2;
    CollSeq *pColl;    /* Collating sequence to use */

    pLeft = pExpr->x.pList->a[1].pExpr;
    pStr2 = sqlite3ExprDup(db, pStr1, 0);
    if( !db->mallocFailed ){
      u8 c, *pC;       /* Last character before the first wildcard */
      pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
      c = *pC;
................................................................................
        if( c=='A'-1 ) isComplete = 0;   /* EV: R-64339-08207 */


        c = sqlite3UpperToLower[c];
      }
      *pC = c + 1;
    }
    pColl = sqlite3FindCollSeq(db, SQLITE_UTF8, noCase ? "NOCASE" : "BINARY",0);


    pNewExpr1 = sqlite3PExpr(pParse, TK_GE, 
                     sqlite3ExprSetColl(sqlite3ExprDup(db,pLeft,0), pColl),

                     pStr1, 0);
    idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
    testcase( idxNew1==0 );
    exprAnalyze(pSrc, pWC, idxNew1);

    pNewExpr2 = sqlite3PExpr(pParse, TK_LT,
                     sqlite3ExprSetColl(sqlite3ExprDup(db,pLeft,0), pColl),

                     pStr2, 0);
    idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
    testcase( idxNew2==0 );
    exprAnalyze(pSrc, pWC, idxNew2);
    pTerm = &pWC->a[idxTerm];
    if( isComplete ){
      pWC->a[idxNew1].iParent = idxTerm;
      pWC->a[idxNew2].iParent = idxTerm;

*/
#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}

/*
** Commute a comparison operator.  Expressions of the form "X op Y"
** are converted into "Y op X".
**
** If left/right precendence rules come into play when determining the
** collating
** side of the comparison, it remains associated with the same side after
** the commutation. So "Y collate NOCASE op X" becomes 
** "X op Y". This is because any collation sequence on
** the left hand side of a comparison overrides any collation sequence 
** attached to the right. For the same reason the EP_Collate flag
** is not commuted.
*/
static void exprCommute(Parse *pParse, Expr *pExpr){
  u16 expRight = (pExpr->pRight->flags & EP_Collate);
  u16 expLeft = (pExpr->pLeft->flags & EP_Collate);
  assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
  if( expRight==expLeft ){
    /* Either X and Y both have COLLATE operator or neither do */
    if( expRight ){
      /* Both X and Y have COLLATE operators.  Make sure X is always
      ** used by clearing the EP_Collate flag from Y. */
      pExpr->pRight->flags &= ~EP_Collate;
    }else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){


      /* Neither X nor Y have COLLATE operators, but X has a non-default
      ** collating sequence.  So add the EP_Collate marker on X to cause
      ** it to be searched first. */
      pExpr->pLeft->flags |= EP_Collate;
    }
  }
  SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
  if( pExpr->op>=TK_GT ){
    assert( TK_LT==TK_GT+2 );
    assert( TK_GE==TK_LE+2 );
    assert( TK_GT>TK_EQ );
    assert( TK_GT<TK_LE );
    assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
................................................................................
  ){
    Expr *pLeft;       /* LHS of LIKE/GLOB operator */
    Expr *pStr2;       /* Copy of pStr1 - RHS of LIKE/GLOB operator */
    Expr *pNewExpr1;
    Expr *pNewExpr2;
    int idxNew1;
    int idxNew2;
    Token sCollSeqName;  /* Name of collating sequence */

    pLeft = pExpr->x.pList->a[1].pExpr;
    pStr2 = sqlite3ExprDup(db, pStr1, 0);
    if( !db->mallocFailed ){
      u8 c, *pC;       /* Last character before the first wildcard */
      pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
      c = *pC;
................................................................................
        if( c=='A'-1 ) isComplete = 0;   /* EV: R-64339-08207 */


        c = sqlite3UpperToLower[c];
      }
      *pC = c + 1;
    }
    sCollSeqName.z = noCase ? "NOCASE" : "BINARY";
    sCollSeqName.n = 6;
    pNewExpr1 = sqlite3ExprDup(db, pLeft, 0);
    pNewExpr1 = sqlite3PExpr(pParse, TK_GE, 

           sqlite3ExprSetCollByToken(pParse,pNewExpr1,&sCollSeqName),
           pStr1, 0);
    idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
    testcase( idxNew1==0 );
    exprAnalyze(pSrc, pWC, idxNew1);
    pNewExpr2 = sqlite3ExprDup(db, pLeft, 0);
    pNewExpr2 = sqlite3PExpr(pParse, TK_LT,

           sqlite3ExprSetCollByToken(pParse,pNewExpr2,&sCollSeqName),
           pStr2, 0);
    idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
    testcase( idxNew2==0 );
    exprAnalyze(pSrc, pWC, idxNew2);
    pTerm = &pWC->a[idxTerm];
    if( isComplete ){
      pWC->a[idxNew1].iParent = idxTerm;
      pWC->a[idxNew2].iParent = idxTerm;