private void gridTeachers_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
DataGridViewRow row = gridTeachers.SelectedRows[0];
int teacherId = Convert.ToInt32(row.Cells["TeacherId"].Value);
String name = row.Cells["TeacherName"].Value.ToString();
String surname = row.Cells["TeacherSurname"].Value.ToString();
String dept = row.Cells["Department"].Value.ToString();
BLAdmin bl = new BLAdmin();
bl.UpdateTeacher(teacherId, name, surname, dept);
gridTeachers.DataSource = bl.GetTeachers(txtNameFilter.Text, txtSurnameFilter.Text, comboBoxDept.GetItemText(comboBoxDept.SelectedItem));
}