private void deleteQuestion() { int questId = 0; if (comboBox2.SelectedItem != null) { questId = int.Parse(comboBox2.Text.ToString().Split(',')[0]); } else { MessageBox.Show("Please select course id", "Waring"); return; } OnlineExam ent = new OnlineExam(); var ques = (from q in ent.Questions where q.QuesId == questId select q).First(); int courseId = (int)ques.CrsId; try { ent.Delete_Question(questId); } catch (Exception) { } loadCourse(); loadQuestions(courseId); }