主题：下拉框过滤

这个是"combobox2"和"combobox3" enter中的代码

Dim cmb As WinForm.ComboBox = e.Sender
Dim str As String = e.Form.Controls("ComboBox1").Value
cmb.ComboList = DataTables("driverinfo").GetComboListString("姓名", "车号 = '" & str & "'")

我想实现当"combobox2"选定的"姓名","combobox3"中不再显示,请教大家,"combobox3"过滤条件要怎么写.