private void OnButtonCreateClick(object sender, EventArgs e)
{
int index = this.cbSubjects.SelectedIndex;
if (index < 0 || index >= avaialableSubjects.Count)
{
return;
}
var sj = avaialableSubjects[index];
var report = new SubjectReport();
SQLConnections.FillResultReportsBySubject(this.teacherID, sj.ID, this.start, this.end, report);
this.Close();
new SubjectReportForm(report).ShowDialog();
}