如何禁用vb.net中自動選擇的組合框

Question

我將組合框綁定到新的數據源，它會自動選擇第一項。我該如何禁用？
這是我的代碼：

Private Sub item_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
     Dim obj As New config 


     con1 = New SqlConnection 
     con1 = obj.getcontion() 
     con1.Open() 



     da = New SqlDataAdapter("select * from item", con1) 
     ds = New DataSet 
     da.Fill(ds, "item") 
     cmbItem.DataSource = ds 
     cmbItem.DisplayMember = "item.itemname" 


    End Sub 

Answer 1

爲了防止combobox被選中。

cmbItem.DataSource = ds 
cmbItem.SelectedIndex=-1 

注意：如果您設置SelectedIndex屬性-1後與datasource結合combobox。

---

顯示自定義文本（ 「​​」），

da = New SqlDataAdapter("select * from item", con1) 
ds = New DataSet 
da.Fill(ds, "item") 
Dim firstRow As DataRow = ds.Tables("item").NewRow 
firstRow("itemname") = "Select an item" 
ds.Tables("item").Rows.InsertAt(firstRow, 0) 
cmbItem.DataSource = ds 
cmbItem.DisplayMember = "item.itemname" 
cmbItem.SelectedIndex = 0