/// <summary>
        /// 选课
        /// </summary>
        /// <param name="stuId"></param>
        /// <param name="teacherCourseId"></param>
        /// <returns></returns>
        public bool ChooseCourse(string stuId, string teacherCourseId)
        {
            Student        student        = studengDAL.SelectStudentById(stuId);
            Teacher_course teacher_Course = teacherCourseDAL.SelectById(teacherCourseId);

            if (student == null || teacher_Course == null)
            {
                return(false);
            }
            courseDAL.ChooseCourse(student, teacher_Course);
            return(true);
        }