private int GetNextStudentID()
        {
            command.CommandText = "SELECT IDENT_CURRENT ('admn') + IDENT_INCR ('admn')";
            try
            {
                connection.Open();
                int nextID = Convert.ToInt32(command.ExecuteScalar());// here i am getting error
                return nextID;
            }
            catch (SqlException ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                connection.Close();
            }
            return 0;
        }