public string InsertRecord(string userid, string username, string password, int level)
        {

            if (Open() )
            {
                string vSQL = "Insert Into [dbo].[usermaster] ([userid], [username], [password], [userlevel]) values('" + userid + "', '" + username + "', '" + password + "', "+ level.ToString() +") ";
                SqlCommand cmd;
                cmd = new SqlCommand(vSQL, con);
                cmd.ExecuteNonQuery();
                return "Record Saved successfully!";
            }
            else
            {
                return "Insert data unsuccessful! - Connection Failed! ";
            }
        }

        public string UpdateRecord(string userid, string username, string password, int level)
        {

            if (Open())
            {
                string vSQL = " Update [dbo].[usermaster] set username = '"+ username+"',  password='"+ password +"', userlevel="+ level+" where userid='"+ userid +"' ";
                SqlCommand cmd;
                cmd = new SqlCommand(vSQL, con);
                cmd.ExecuteNonQuery();
                return "Record Updated successfully!";
            }
            else
            {
                return "Update data unsuccessful! - Connection Failed! ";
            }
        }

        public string DeleteRecord(string userid)
        {

            if (Open())
            {
                string vSQL = " Delete from [dbo].[usermaster] where userid='"+ userid +"' ";
                SqlCommand cmd;
                cmd = new SqlCommand(vSQL, con);
                cmd.ExecuteNonQuery();
                return "Record Deleted successfully!";
            }
            else
            {
                return "Delete data unsuccessful! - Connection Failed! ";
            }
        }

        public List<Usermaster> RetrieveRecord()
        {
            var model = new List<Usermaster>();
            if (Open())
            {
                SqlCommand cmd;
                cmd = new SqlCommand("Select * from [dbo].[usermaster] ", con);
                SqlDataReader rdr = cmd.ExecuteReader();
                var usermaster = new Usermaster();
                while(rdr.Read())
                {
                    usermaster.userid = rdr["userid"].ToString();
                    usermaster.username = rdr["username"].ToString();
                    usermaster.password = rdr["password"].ToString();
                    usermaster.userlevel = rdr["userlevel"].ToString();
                    model.Add(usermaster);
                }
            }
            return model;
        }