<asp:Button ID="btn" runat="server" OnClick="btnView_Click" CausesValidation="true" Text="Search" />  

<asp:gridview id="gv"  allowpaging="true" allowsorting="true" runat="server" autogeneratecolumns="False" datakeynames="StudentID"  datasourceid="SqlDataSource1" >

<Columns>

        <asp:BoundField DataField="IDString" HeaderText="Student ID" SortExpression="IDString" />

</Columns>

</asp:gridview>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:************* %>"

            CancelSelectOnNullParameter="false" SelectCommand="Select*****"

            OnSelecting="on_Selecting">

            <SelectParameters>

                <asp:Parameter Name="*****" />

           </SelectParameters>

</asp:SqlDataSource>

 

   

 1 

 

protected

 

void

 on_Selecting(

object

 sender, SqlDataSourceSelectingEventArgs e)

 2 

    {

 3 

        

string

 strFilter 

=

 GetFilterStr();

 4 

        SqlDataSource1.FilterExpression 

=

 strFilter;

 5 

    }

 6 

 7 

    

private

 

string

 GetFilterStr()

 8 

    {

 9 

        StringBuilder strFilter 

=

 

new

 StringBuilder();

10 

        strFilter.Append(

"

1=1

"

);

11 

12 

        strFilter.AppendFormat(

"

 and (XXXXX='{0}')

"

, XXXX);

13 

    }

14 

15 

16 

17 

    

protected

 

void

 btnView_Click(

object

 sender, EventArgs e)

18 

    {

19 

        SqlDataSource1.SelectParameters[

"

SchoolID

"

].DefaultValue 

=

 SchoolDropDownList1.SelectedValue.ToString();

20 

        gv.DataBind();

21 

    }

22 

23