VB.net. how to do databind for the all dropdownlist in repeater

I have a dropdownlist in my repeater, the dropdownlist is databound by a datasource. Originally all the dropdownlist will have all the same item option. I try to do if one of the showing dropdownlist is selected one option, then in other dropdownlist this option will disapper.

here is the asp:

<asp:Repeater ID="UnitMatchRepeater" runat="server" DataSourceID="OldUnitsDataSource" >
    <ItemTemplate>
       <tr>
       <td>
       <asp:Label ID="OldUnitNumber" runat="server" Text='<%# Eval("Vehicle")%>' value='<%#Container.DataItem("LinkNumber") %>'></asp:Label>
       </td>
       <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
        <td>
        <asp:DropDownList ID="NewUnitsDropDownBox" runat="server" DataSourceID="NewUnitsDataSource" DataTextField="UnitNumber"
            DataValueField="LinkNumber" OnDataBound="call_it" AutoPostBack="true" value='<%# Container.DataItem("LinkNumber")%>'></asp:DropDownList>
        </td>
        <br/>
        </tr>
    </ItemTemplate>
    </asp:Repeater>
<asp:SqlDataSource ID="OldUnitsDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:minotaurSQLConnectionString %>">
    </asp:SqlDataSource>
    <br />
    <asp:SqlDataSource ID="NewUnitsDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:minotaurSQLConnectionString %>" 
        SelectCommand="SELECT Minotaur.dbo.Units.LinkNumber AS LinkNumber, RTAFleet.dbo.vehfile.vehicle AS UnitNumber FROM RTAFleet.dbo.vehfile INNER JOIN Minotaur.dbo.Units ON RTAFleet.dbo.vehfile.link_number = Minotaur.dbo.Units.LinkNumber AND Minotaur.dbo.Units.AcquisitionOrderID = @AcquisitionOrderID AND Minotaur.dbo.Units.SnapShotID = 1 AND Minotaur.dbo.Units.OldLinkNumber IS NULL">
        <SelectParameters>
            <asp:QueryStringParameter Name="AcquisitionOrderID" QueryStringField="orderID" 
                Type="Int32" />
        </SelectParameters>
    </asp:SqlDataSource>

here is the code behind:

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim LinkNoArray开发者_如何学C As String() = Request.QueryString("linkNumber").Split(",")
        Dim SqlStr As String = "SELECT Vehicle = CASE WHEN ISNUMERIC(RTAFleet.dbo.vehfile.vehicle) = 1 AND RTAFleet.dbo.vehfile.vehicle IS NOT NULL THEN RTAFleet.dbo.vehfile.vehicle ELSE  RTAFleet.dbo.vehfile.veh_xref_num END, RTAFleet.dbo.vehfile.link_number AS LinkNumber FROM RTAFleet.dbo.vehfile INNER JOIN Minotaur.dbo.Units ON RTAFleet.dbo.vehfile.link_number = Minotaur.dbo.Units.LinkNumber AND  Minotaur.dbo.Units.SnapShotID = 1 WHERE "
        For Each Str As String In LinkNoArray
            SqlStr = SqlStr & " Minotaur.dbo.Units.LinkNumber = " & Trim(Str) & " OR"
        Next
        If Not Page.IsPostBack Then
            SqlStr = Left(SqlStr, (SqlStr.Length - 2))
            OldUnitsDataSource.SelectCommand = SqlStr
            UnitMatchRepeater.DataBind()
        End If



End Sub

Private Sub UnitMatchRepeater_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles UnitMatchRepeater.ItemCreated
        If Not e.Item.ItemType = ListItemType.Item And Not e.Item.ItemType = ListItemType.AlternatingItem Then
            Exit Sub
        End If
        Dim NewUnitsDDB As DropDownList = e.Item.FindControl("NewUnitsDropDownBox")

        AddHandler NewUnitsDDB.SelectedIndexChanged, AddressOf NewUnitsDDB_SelectedIndexChanged
    End Sub

    Protected Sub NewUnitsDDB_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim linkNo As String = CType(sender, DropDownList).SelectedValue
        Dim sqlStr As String = "UPDATE dbo.Units SET OldLinkNumber = @oldLinkNum WHERE LinkNumber = @newLinkNum"
        Dim con As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("minotaurSQLConnectionString").ConnectionString)
        Dim cmd As SqlCommand = New SqlCommand(sqlStr, con)
        cmd.Parameters.Add("@oldLinkNum", SqlDbType.Int).Value = CType(sender, DropDownList).Attributes("value")
        cmd.Parameters.Add("@newLinkNum", SqlDbType.Int).Value = CInt(linkNo)

        con.Open()
        cmd.ExecuteNonQuery()
        con.Close()

        dlistdatabinding()


    End Sub

 Private Sub dlistdatabinding()

        For Each rep As RepeaterItem In UnitMatchRepeater.Items
            Dim list As DropDownList = rep.FindControl("NewUnitsDropDownBox")
            list.DataBind()
        Next

End Sub

Please help to find out how to make it works. thanks

Put your drop down list data binding code in the ItemDataBound event of your repeater. This is the event that fires every time it creates a "row" in your repeater. From there you can find the individual drop down list in the item.

The added benefit to this is that as each item is data bound, you could potentially change the contents of the drop down list based on the data you are working with.