title: Duplicate items in dropdownlist!
body: <p>Ok I really hope you guys can help me with this, I've spent the past 2 days trying to figure it out and I think I'm about to throw my computer out the window, so I thought I might as well ask here first:</p>
  
  <p>I'm designing a web page with two dropdownlists, one for the Make of a car, the other for the Model, both bound to a database with separate SQLDataSources, and using a distinct statement. I add "All" at the top of both by setting appendDataBoundItems = true and adding items named all. Then when I fill the Make with a querystring all the model items get added twice (but only the databound items).</p>
  
  <p>Here's my code:</p>
  
  <pre><code>    &lt;asp:DropDownList ID="DropDownMake" runat="server" 
          DataSourceID="SqlMakes" DataTextField="Make" DataValueField="Make" 
          AppendDataBoundItems="True" EnableViewState="False" AutoPostBack="True"&gt;
          &lt;asp:ListItem Selected="True" Value="All"&gt;All&lt;/asp:ListItem&gt;
      &lt;/asp:DropDownList&gt;
      &lt;asp:DropDownList ID="DropDownModel" runat="server" 
          AppendDataBoundItems="True" AutoPostBack="True" DataSourceID="SqlModels" 
          DataTextField="Model" DataValueField="Model" EnableViewState="False"&gt;
          &lt;asp:ListItem&gt;All&lt;/asp:ListItem&gt;
      &lt;/asp:DropDownList&gt;
      &lt;asp:SqlDataSource ID="SqlMakes" runat="server" 
          ConnectionString="&lt;%$ ConnectionStrings:ConnectionString %&gt;" 
          SelectCommand="SELECT DISTINCT [Make] FROM [Parts]"&gt;
      &lt;/asp:SqlDataSource&gt;
      &lt;asp:SqlDataSource ID="SqlModels" runat="server" 
          ConnectionString="&lt;%$ ConnectionStrings:ConnectionString %&gt;" 
  
  
          SelectCommand="SELECT DISTINCT [Model] FROM [Parts] WHERE ([Make] = @Make)"&gt;
          &lt;SelectParameters&gt;
              &lt;asp:ControlParameter ControlID="DropDownMake" Name="Make" 
                  PropertyName="SelectedValue" /&gt;
          &lt;/SelectParameters&gt;
      &lt;/asp:SqlDataSource&gt;
  </code></pre>
  
  <p>'And in the VB file:</p>
  
  <pre><code>Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
      DropDownMake.SelectedValue = Request.QueryString("Make")
      DropDownModel.SelectedValue = Request.QueryString("Model")
  End Sub
  </code></pre>
  
  <p>If I remove the line "DropDownMake.SelectedValue = Request.QueryString("Make")" it doesnt produce duplicates anymore. What is going on?? I swear I've spent more time developing entire iphone apps, if anyone helps figure this out I think I'm going to have to make an award for you.</p>
  
  <p>Thank you!!</p>