//---fill list lecturers public void fillLecturers_list(ListBox lb_nameLecturers, string nameCourse, int day, int hour, CoursesDB coursedb) { //---input to list all lecturers of this course List <string> IDlecturersList = new List <string>(); char semester; try { con.OpenCon(); com = new SqlCommand("SELECT * FROM LecturerToCourses WHERE NameCourse = '" + nameCourse + "'", con.GetCon()); SqlDataReader rdr = com.ExecuteReader(); while (rdr.Read()) { IDlecturersList.Add(rdr[1].ToString()); } con.CloseCon(); // lb_nameLecturers.DataSource = IDlecturers; } catch (Exception ex) { MessageBox.Show(ex.Message); } semester = coursedb.GetSemeterByCourse(nameCourse); int numh = coursedb.getNumHour(lb_nameLecturers.Text, 1); //---check if each lecturer can learning in this time checkPreferencesLecturers(lb_nameLecturers, IDlecturersList, day, hour, semester, numh); }