public override bool DeleteToDB(DBManager db) { if (_teacherID <= 0) return false; // not realy delete in DB. just mark flag return (db.Execute("UPDATE teacher SET is_active=0 WHERE teacher_id=" + _teacherID) > 0) ? true : false; // return (db.Delete("teacher", "teacher_id=" + _teacherID) > 0) ? true : false; }