public function index()
{
$centers = ExamCenter::get();
$chosen_centers = ExamCenter::select('exam_centers.*')->join('student_exam_center AS sec', function ($join) {
$join->on('sec.exam_center_id', '=', 'exam_centers.id')->where('sec.student_id', '=', student()->id)->where('sec.semester_id', '=', semester()->id);
})->whereNull('sec.id')->get();
return $chosen_centers;
return view('students::profile.exams.centers.index', compact('centers', 'chosen_centers'));
}
