vb.net combobox population getting index of the 1st combobox

问题

I populated my combobox1 with this code in load

sql = "select name1,id1 from table1"
da = New Odbc.OdbcDataAdapter(sql, con)
da.Fill(ds, "cbtbl1")
ComboBox1.DataSource = ds.Tables("cbtbl1")
ComboBox1.DisplayMember = ds.Tables("cbtbl1").Columns("name1").Caption

I have my 2nd combobox2 related to combobox1. I inserted this code in combobox1 selectedvaluechanged. This to change to value of combobox2 based on their related ids

sql = "select name2,id2 from table2 where id1=" & ???????
da = New Odbc.OdbcDataAdapter(sql, con)
da.Fill(ds, "cbtbl2")
ComboBox2.DataSource = ds.Tables("cbtbl2")
ComboBox2.DisplayMember = ds.Tables("cbtbl2").Columns("name2").Caption

In my code i have question marks. It supposed to be the id of table1 which i don't know how to get :( or what to put

回答1:

You should set the ValueMember of Combobox1 to be the ID you retrieved from the database and the use the SelectedValue property to retrieve the ID of the selected item.

I don't think it's gonna work unless you specify the ValueMember property when you databind Combobox1, so don't forget to do that first.

OK, I knocked something together quickly with a database I am working on at the moment (it's OLEDB, but shouldn't matter for this)

Public Sub New()

    ' This call is required by the designer.
    InitializeComponent()

    ' Add any initialization after the InitializeComponent() call.

    Dim ds As New DataSet()
    Dim test As New OleDbDataAdapter("SELECT [ID], [名前] FROM [Tレイヤ管理]", DBConnections.PrimaryAccessDBConnection)
    Call test.Fill(ds, "testTable")

    Me.ComboBox1.DataSource = ds.Tables("testTable")
    Me.ComboBox1.ValueMember = "ID"
    Me.ComboBox1.DisplayMember = "名前"

    AddHandler Me.ComboBox1.SelectedValueChanged, AddressOf Something

End Sub

Private Sub Something(sender As Object, e As EventArgs)

    Call MessageBox.Show(String.Format("ID {0}", Me.ComboBox1.SelectedValue))

End Sub

I get the ID showing just fine with this.

UPDATE:

If this still doesn't work then you can get the selected item this way:

Private Sub Something(sender As Object, e As EventArgs)

    Dim selectedItem As DataRowView = CType(Me.ComboBox1.SelectedItem, DataRowView)

    Call MessageBox.Show(String.Format("ID {0} Name {1}", New Object() {selectedItem("ID"), selectedItem("名前")}))

End Sub

来源：https://stackoverflow.com/questions/15426218/vb-net-combobox-population-getting-index-of-the-1st-combobox

标签

vb.net

combobox