private void mnuDelete_Click(object sender, EventArgs e) { if (!clsValidation.ValidateComboBox(cmbTeacherID)) { return; } if (!clsValidation.ValidateComboBox(cmbCourseID)) { return; } clsTeacherCourse objTeacherCourse = new clsTeacherCourse(Convert.ToInt32(cmbTeacherID.Text), Convert.ToInt32(cmbCourseID.Text)); objTeacherCourse.Delete(); MessageBox.Show("Teacher-Course record successfully deleted!"); objTeacherCourse.ViewAll(dgvTeacherCourse); }