public ActionResult DeleteStudentTeacher(StudentTeacherInfo studentTeacherInfo)
        {
            try
            {
                StudentTeacher studentTeacher = db.StudentTeachers.Where(st => st.StudentId == studentTeacherInfo.studentId && st.TeacherId == studentTeacherInfo.teacherId).FirstOrDefault();

                if (studentTeacher != null)
                {
                    db.StudentTeachers.Remove(studentTeacher);
                    db.SaveChanges();

                    return(Json(new
                    {
                        msg = "Successfully Deleted This Teacher From The Student"
                    }));
                }


                else
                {
                    return(Json(new
                    {
                        msg = "Can't Delete This Teacher From The Student"
                    }));
                }
            }
            catch
            {
                return(Json(new
                {
                    msg = "Can't Delete This Teacher From The Student"
                }));
            }
        }
        public ActionResult AddTeacher(StudentTeacherInfo studentTeacherInfo)
        {
            try
            {
                var teacherExist = db.StudentTeachers.Where(st => st.StudentId == studentTeacherInfo.studentId && st.TeacherId == studentTeacherInfo.teacherId).FirstOrDefault();
                if (teacherExist == null)
                {
                    StudentTeacher studentTeacher = new StudentTeacher();
                    studentTeacher.TeacherId = studentTeacherInfo.teacherId;
                    studentTeacher.StudentId = studentTeacherInfo.studentId;
                    if (ModelState.IsValid)
                    {
                        db.StudentTeachers.Add(studentTeacher);
                        db.SaveChanges();
                    }

                    return(Json(new
                    {
                        msg = "Successfully Added This Teacher To The Student"
                    }));
                }
                else
                {
                    return(Json(new
                    {
                        msg = "This Teacher Is Already Applied To The Student"
                    }));
                }
            }
            catch
            {
                return(Json(new
                {
                    msg = "Can't Add This Teacher To The Student"
                }));
            }
        }