ASP.NET

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SelectCommand="SELECT * FROM [datatable] WHERE ([afield] = @afield) OR ([bfield] = @bfield) "><br />
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SelectParameters<br />
   ControlParameter ControlID="DropDownList1" Name="afield" PropertyName="SelectedValue" Type="String" /><br />
   ControlParameter ControlID="DropDownList2" Name="bfield" PropertyName="SelectedValue" Type="String" /><br />
SelectParameters><br />
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Dropdown lists:<br />
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  <asp:dropdownlist id="DropDownList1" runat="server" autopostback="True"><br />
            <asp:listitem>Select an item</asp:listitem><br />
            <asp:listitem>A</asp:listitem><br />
            <asp:listitem>B</asp:listitem>            <br />
        </asp:dropdownlist><br /><br /><br />
        <br />
        <asp:dropdownlist id="DropDownList2" runat="server" autopostback="True"><br />
            <asp:listitem>Select an item</asp:listitem><br />
            <asp:listitem>Closed</asp:listitem><br />
            <asp:listitem>Open</asp:listitem><br />
        </asp:dropdownlist><br />
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Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load<br />
        If DropDownList1.SelectedIndex.Equals(0) Then<br />
            datatable.SelectCommand = ("SELECT * FROM [table]")<br />
            GridView1.DataBind()<br />
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        End If<br />
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    End Sub