代码放在combobox3的valuechanged 里面

当选择部门时，列表中会对应显示出部门旗下的二级部门。但是现在无论选哪个部门，都会显示同样的二级部门。

帮忙看看下面的代码应该怎么改吧

Dim cmd As New SQLCommand
Dim dt As DataTable
\'Dim dt As DataTable = DataTables("人员信息表")
Dim lst As WinForm.ListBox = e.Form.Controls("ListBox1")
cmd.C
cmd.CommandText = "SE LE C T DISTINCT 部门,二级部门 From {人员信息表}"
dt = cmd.ExecuteReader()

For Each dr As DataRow In dt.Datarows
    Dim drs As List(Of String)
    drs = dt.GetUniqueValues("部门 > \'\' AND 二级部门 > \'\' ","部门")
    For i As Integer = 0 To drs.Count - 1
        If dr("部门") = drs(i) Then
            lst.Items.Add(dr("二级部门"))
        End If
    Next
Next
If Lst.Items.Count > 0 Then
    lst.SelectedIndex = 0
End If