public override object Clone()
        {
            SQLiteSelectStatement select = null;

            if (_select != null)
            {
                select = (SQLiteSelectStatement)_select.Clone();
            }

            SQLiteExistsExpression res = new SQLiteExistsExpression();

            res._select = select;
            return(res);
        }
        public override bool Equals(object obj)
        {
            if (obj == null)
            {
                return(false);
            }

            SQLiteExistsExpression dst = obj as SQLiteExistsExpression;

            if (dst == null)
            {
                return(false);
            }

            if (!RefCompare.Compare(_select, dst._select))
            {
                return(false);
            }

            return(base.Equals(obj));
        }