Private Sub doktorkayit_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 ilDoldur()
 End Sub

Private Sub ilDoldur()
 Dim baglanti As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source='access.mdb'")
 Dim veriler As New DataTable("il")
 Dim adapter As New OleDbDataAdapter("select * from tblil order by il", baglanti)
 adapter.Fill(veriler)
 cbIl.ValueMember = "id"
 cbIl.DisplayMember = "il"
 cbIl.DataSource = veriler
 End Sub
 

 Private Sub cbIl_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbIl.SelectedIndexChanged
 ilceDoldur()
 End Sub

 Private Sub ilceDoldur()
 Dim baglanti As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source='access.mdb'")
 Dim veriler As New DataTable("ilce")
 Dim adapter As New OleDbDataAdapter(String.Format("select * from tblilce where il_ID={0}", cbIl.SelectedValue.ToString), baglanti)
 adapter.Fill(veriler)
 cbIlce.DataSource = veriler
 cbIlce.DisplayMember = "ilce"
 End Sub