private void bAdd_Click(object sender, EventArgs e) { var studyGroupIndex = cbStudyGroup.SelectedIndex; var subjectIndex = cbSubject.SelectedIndex; var studyGroupSubject = new StudyGroupSubjectModel() { SubjectID = _subjects[subjectIndex].Id.Value, StudyGroupID = _studyGroups[studyGroupIndex].Id }; var subjectExist = DbService.StudyGroupSubject(studyGroupSubject.StudyGroupID, studyGroupSubject.SubjectID); if (subjectExist.Count == 0) { EventGenerator.GenerateEventsAfterPairing(studyGroupSubject); DbService.StudyGroupSubjectInsert(studyGroupSubject); } CheckSubjects(); this.Close(); }