protected void lb_studdelete_Click(object sender, EventArgs e)
        {
            LinkButton lb = (LinkButton)sender;
            var        id = int.Parse(lb.CommandArgument);

            var courseToRemove = cc.CourseByID(id);
            var gc             = new GradesControl();

            var gradesToRemove = gc.GetAllGrades().ToList().Where(x => x.CourseID == courseToRemove.Id);

            foreach (var grade in gradesToRemove)
            {
                gc.RemoveGrade(grade);
            }

            var ac = new AttendanceControl();
            var attendanceToRemove = ac.GetAllAttendance().ToList().Where(a => a.CourseID == courseToRemove.Id);

            foreach (var attendance in attendanceToRemove)
            {
                ac.RemoveAttendance(attendance);
            }

            cc.RemoveCourse(courseToRemove);

            Response.Redirect($"Course");
        }
        protected void btn_addCourse_Click(object sender, EventArgs e)
        {
            var    grade = new Grades();
            string param = Request.QueryString["studentID"];

            if (ddl_studCourse.SelectedValue != "0")
            {
                var studID = int.Parse(param);
                grade.Grade     = ddl_studGrade.SelectedValue;
                grade.Completed = chkbox_completed.Checked;
                grade.CourseID  = int.Parse(ddl_studCourse.SelectedValue);
                grade.StudentID = studID;

                var student = sc.StudentsByID(studID);
                var myBool  = student.Grades.FirstOrDefault(x => x.CourseID == grade.CourseID && x.StudentID == grade.StudentID) != null;
                if (myBool)
                {
                    var gc = new GradesControl();
                    gc.UpdateGrade(grade);
                }
                else
                {
                    student.Grades.Add(grade);
                    sc.UpdateStudent(student);
                }
            }

            Response.Redirect($"Course?StudentID={param}");
        }
        protected void LinkButton1_Click(object sender, EventArgs e)
        {
            LinkButton lb = (LinkButton)sender;
            var        id = lb.CommandArgument;

            var gc = new GradesControl();

            int studID               = int.Parse(Request.QueryString["StudentID"]);
            int courseID             = int.Parse(id);
            var studentGradeToRemove = gc.GradeByStudentAndCourseID(studID, courseID);

            gc.RemoveGrade(studentGradeToRemove);

            Response.Redirect($"Course?StudentID={studID}");
        }