selecting an item from dropdownlist display in datagridview

How can I retrieve data from sql database by selecting an item from a drop down list and displaying the selected item information in a data grid view?

following is a code that I have but its not working I can select from a dropdown list but nothing appears in a data grid view

ASP.NET Code:

<

table>

      

<tr>

           

<td>

               

<asp:Label ID="lblShow" runat="server" Text="Select Station ID">asp:Label>

               

<asp:DropDownList ID="ddlshow" runat="server" DataSourceID="SqlDataSource3"

                   

DataTextField="Perway_Status" DataValueField="Perway_Status"

                   

onselectedindexchanged="ddlshow_SelectedIndexChanged">

                   

<asp:ListItem Text="All" Value="All" Selected="True"/>

               

asp:DropDownList>

               

<asp:SqlDataSource ID="SqlDataSource3" runat="server"

                   

ConnectionString="<%$ ConnectionStrings:StatStressConnectionString %>"

                   

                   

SelectCommand="SELECT DISTINCT Stations.Station_ID, Stations.Station_Name, Sections.Section_ID, Sections.Perway_Status, Sections.Equipment_Status, Station_Status_Current.Status_Time FROM Sections INNER JOIN Stations ON Sections.Section_ID = Stations.Section_ID CROSS JOIN Station_Status_Current CROSS JOIN Status_Legend ORDER BY Stations.Station_ID">

               

asp:SqlDataSource>

           

td>

          

      

tr>

      

<tr>

           

<td>

               

<asp:GridView ID="GdvshowAll" runat="server" DataSourceID="SqlDataSource1"

                   

AutoGenerateColumns="False">

                   

<Columns>

                       

<asp:BoundField DataField="Section_Name" HeaderText="Section_Name"

                           

SortExpression="Section_Name" />

                       

<asp:BoundField DataField="Perway_Status" HeaderText="Perway_Status"

                           

SortExpression="Perway_Status" />

                       

<asp:BoundField DataField="Equipment_Status" HeaderText="Equipment_Status"

                           

SortExpression="Equipment_Status" />

                       

<asp:BoundField DataField="Station_ID" HeaderText="Station_ID"

                           

SortExpression="Station_ID" InsertVisible="False" ReadOnly="True" />

                       

<asp:BoundField DataField="Station_Lines" HeaderText="Station_Lines"

                           

SortExpression="Station_Lines" />

                       

<asp:BoundField DataField="Status_Time" HeaderText="Status_Time"

                           

SortExpression="Status_Time" />

                       

<asp:BoundField DataField="Station_Name" HeaderText="Station_Name"

                           

SortExpression="Station_Name" />

                   

Columns>

               

asp:GridView>

               

<asp:SqlDataSource ID="SqlDataSource1" runat="server"

                   

ConnectionString="<%$ ConnectionStrings:StatStressConnectionString %>" SelectCommand=" SELECT DISTINCT

                         Sections.Section_Name, Sections.Perway_Status, Sections.Equipment_Status, Stations.Station_ID, Stations.Station_Lines,

                         Station_Status_Current.Status_Time, Stations.Station_Name

FROM            Sections LEFT OUTER JOIN

                         Stations ON Stations.Section_ID = Sections.Section_ID LEFT OUTER JOIN

                         Station_Status_Current ON Station_Status_Current.Station_ID = Stations.Station_ID AND Station_Status_Current.Station_ID = Stations.Section_ID

WHERE        (Stations.Station_ID = @ddlshow)

ORDER BY Stations.Station_ID ">

                   

<SelectParameters>

                       

<asp:ControlParameter ControlID="ddlshow" Name="ddlShow"

                           

PropertyName="SelectedValue" />

SelectParameters>

asp:SqlDataSource>

td>

tr>

table> 

C# Code:

protected

void ddlshow_SelectedIndexChanged(object sender, EventArgs e)

        {

            SqlDataSource1.DataBind();

            GdvshowAll.DataBind();

        }

       

public override void VerifyRenderingInServerForm(Control control)

        {

           

return;

        }