private void Dodaj_Click(object sender, RoutedEventArgs e) { var con = new KolDb(); var max = con.EMPs.Max(d => d.EMPNO); var deptno = con.DEPTs .Where(x => x.DNAME == Ddname.SelectedItem.ToString()) .Select(x => x.DEPTNO).First(); EMP tempemp = new EMP() { EMPNO = max + 1, ENAME = Eename.Text, JOB = Jjob.Text, DEPTNO = deptno, }; con.EMPs.Add(tempemp); con.SaveChanges(); Odswiez(); }