public function updateStudent(Student $student)
 {
     $sql = "UPDATE Student SET FirstName = ?, LastName=?, gender=? , dob= ?, username = ?, password = ?, approved = ?" . "WHERE student_Id = ?";
     $params = array($student->getFirstName(), $student->getLastName(), $student->getGender(), $student->getDob()->format("y/m/d"), $student->getUsername(), $student->getPassword(), $student->isApproved(), $student->getStudentId());
     $query = $this->db->prepare($sql);
     $res = $query->execute($params);
     return $res;
 }