public string UnAssignCourses()
        {
            int rowAffected  = _courseAssignGateway.UnAssignCourses();
            int rowAffected2 = new EnrollCourseGateway().DisEnrollCourses();

            if (rowAffected2 > 0 && rowAffected > 0)
            {
                return("Unassign Courses Successfully");
            }
            else
            {
                return("Failed");
            }
        }