[superwoofer]

da.SelectCommand = New SqlClient.SqlCommand("select * from dept ", conn)
If ds.Tables.Contains("dd") Then
ds.Tables("dd").Clear()
End If
da.Fill(ds, "dd")
DataGridView1.DataSource = ds.Tables("dd")

ComboBox1.DataSource = ds.Tables("dd")
ComboBox1.ValueMember = "dept_id"
ComboBox1.DisplayMember = ("dept_name")