public string EnrollCourseSave(EnrollCourses enroll)
        {
            bool isStudentAssigned = studentGateway.IsStudentAssigned(enroll);

            if (isStudentAssigned)
            {
                return("This course has already been assigned to this student");
            }

            else
            {
                int row = studentGateway.EnrollCourseSave(enroll);
                if (row > 0)
                {
                    return("The course has been assigned to the student successfully");
                }
                else
                {
                    return("An error occured");
                }
            }
        }