SQLite

  if( pLeft==0  ){
    return pRight;
  }else if( pRight==0 ){
    return pLeft;
  }else if( ExprAlwaysFalse(pLeft) || ExprAlwaysFalse(pRight) ){
    sqlite3ExprUnmapAndDelete(pParse, pLeft);
    sqlite3ExprUnmapAndDelete(pParse, pRight);
    return sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
  }else{
    return sqlite3PExpr(pParse, TK_AND, pLeft, pRight);
  }
}

/*
** Construct a new expression node for a function with multiple

    sqlite3VdbeAddOp2(v, OP_Integer, 0, dest.iSDParm);
    VdbeComment((v, "Init EXISTS result"));
  }
  if( pSel->pLimit ){
    /* The subquery already has a limit.  If the pre-existing limit is X
    ** then make the new limit X<>0 so that the new limit is either 1 or 0 */
    sqlite3 *db = pParse->db;
    pLimit = sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0);
    if( pLimit ){
      pLimit->affExpr = SQLITE_AFF_NUMERIC;
      pLimit = sqlite3PExpr(pParse, TK_NE,
                            sqlite3ExprDup(db, pSel->pLimit->pLeft, 0), pLimit);
    }
    sqlite3ExprDelete(db, pSel->pLimit->pLeft);
    pSel->pLimit->pLeft = pLimit;
  }else{
    /* If there is no pre-existing limit add a limit of 1 */
    pLimit = sqlite3ExprAlloc(pParse->db, TK_INTEGER, &sqlite3IntTokens[1], 0);
    pSel->pLimit = sqlite3PExpr(pParse, TK_LIMIT, pLimit, 0);
  }
  pSel->iLimit = 0;
  if( sqlite3Select(pParse, pSel, &dest) ){
    return 0;
  }
  pExpr->iTable = rReg = dest.iSDParm;

/*
** Hash table for global functions - functions common to all
** database connections.  After initialization, this table is
** read-only.
*/
FuncDefHash sqlite3BuiltinFunctions;

/*
** Constant tokens for values 0 and 1.
*/
const Token sqlite3IntTokens[] = {
   { "0", 1 },
   { "1", 1 }
};

#ifdef VDBE_PROFILE
/*
** The following performance counter can be used in place of
** sqlite3Hwtime() for profiling.  This is a no-op on standard builds.
*/
sqlite3_uint64 sqlite3NProfileCnt = 0;
#endif

      **      expr1 IN ()
      **      expr1 NOT IN ()
      **
      ** simplify to constants 0 (false) and 1 (true), respectively,
      ** regardless of the value of expr1.
      */
      sqlite3ExprUnmapAndDelete(pParse, A);
      A = sqlite3ExprAlloc(pParse->db, TK_INTEGER,&sqlite3IntTokens[N],1);
    }else{
      A = sqlite3PExpr(pParse, TK_IN, A, 0);
      if( A ){
        A->x.pList = Y;
        sqlite3ExprSetHeightAndFlags(pParse, A);
      }else{
        sqlite3ExprListDelete(pParse->db, Y);

** within the HAVING expression with a constant "1".
*/
static int havingToWhereExprCb(Walker *pWalker, Expr *pExpr){
  if( pExpr->op!=TK_AND ){
    Select *pS = pWalker->u.pSelect;
    if( sqlite3ExprIsConstantOrGroupBy(pWalker->pParse, pExpr, pS->pGroupBy) ){
      sqlite3 *db = pWalker->pParse->db;
      Expr *pNew = sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[1], 0);
      if( pNew ){
        Expr *pWhere = pS->pWhere;
        SWAP(Expr, *pNew, *pExpr);
        pNew = sqlite3ExprAnd(pWalker->pParse, pWhere, pNew);
        pS->pWhere = pNew;
        pWalker->eCode = 1;
      }

int sqlite3ValueFromExpr(sqlite3 *, Expr *, u8, u8, sqlite3_value **);
void sqlite3ValueApplyAffinity(sqlite3_value *, u8, u8);
#ifndef SQLITE_AMALGAMATION
extern const unsigned char sqlite3OpcodeProperty[];
extern const char sqlite3StrBINARY[];
extern const unsigned char sqlite3UpperToLower[];
extern const unsigned char sqlite3CtypeMap[];
extern const Token sqlite3IntTokens[];
extern SQLITE_WSD struct Sqlite3Config sqlite3Config;
extern FuncDefHash sqlite3BuiltinFunctions;
#ifndef SQLITE_OMIT_WSD
extern int sqlite3PendingByte;
#endif
#endif
#ifdef VDBE_PROFILE

    ** function accepts zero arguments, and there are no other columns
    ** selected (e.g. "SELECT row_number() OVER () FROM t1"), it is possible
    ** that pSublist is still NULL here. Add a constant expression here to 
    ** keep everything legal in this case. 
    */
    if( pSublist==0 ){
      pSublist = sqlite3ExprListAppend(pParse, 0, 
          sqlite3ExprAlloc(db, TK_INTEGER, &sqlite3IntTokens[0], 0)
      );
    }

    pSub = sqlite3SelectNew(
        pParse, pSublist, pSrc, pWhere, pGroupBy, pHaving, pSort, 0, 0
    );
    p->pSrc = sqlite3SrcListAppend(pParse, 0, 0, 0);