private bool cmpStr(string s, DateTime c1, DateTime c2)
        {
            if (s == ">") return c1 > c2;
            else if (s == ">=") return c1 >= c2;
            else if (s == "==") return c1 == c2;
            else if (s == "<=") return c1 <= c2;
            else if (s == "<") return c1 < c2;
            else return false;
        }

        private bool cmpStr(string s, int c1, int c2)
        {
            if (s == ">") return c1 > c2;
            else if (s == ">=") return c1 >= c2;
            else if (s == "==") return c1 == c2;
            else if (s == "<=") return c1 <= c2;
            else if (s == "<") return c1 < c2;
            else return false;
        }

        private bool cmpStr(string s, double c1, double c2)
        {
            if (s == ">") return c1 > c2;
            else if (s == ">=") return c1 >= c2;
            else if (s == "==") return c1 == c2;
            else if (s == "<=") return c1 <= c2;
            else if (s == "<") return c1 < c2;
            else return false;
        }