ASP.NET网格视图中的排序问题

Question

我在我的asp.net项目中使用了Gridview，并启用了如下的soring功能。

<asp:GridView ID="Imp_Report" runat="server" AllowPaging="True" 
        AllowSorting="True" AutoGenerateColumns="False" CellPadding="4" 
        Font-Bold="False" Font-Names="Verdana" 
        ForeColor="#333333" GridLines="None" HorizontalAlign="Left" PageSize="20" 
        style="margin-right: 288px" Width="900px" 
        onselectedindexchanged="Imp_Report_SelectedIndexChanged" 
        DataSourceID="ReportConn">
        <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
        <Columns>
            <asp:CommandField ShowSelectButton="True" />
            <asp:BoundField DataField="Report_No" HeaderText="Report_No" 
                InsertVisible="False" ReadOnly="True" SortExpression="Report_No" />
            <asp:BoundField DataField="Project_Name" HeaderText="Project_Name" 
                SortExpression="Project_Name" />
            <asp:BoundField DataField="Start_Time" HeaderText="Start_Time" 
                SortExpression="Start_Time" />
            <asp:BoundField DataField="Duration (In Min)" HeaderText="Duration (In Min)" 
                ReadOnly="True" SortExpression="Duration (In Min)" />
            <asp:BoundField DataField="Engineer_Name" HeaderText="Engineer_Name" 
                SortExpression="Engineer_Name" />
            <asp:BoundField DataField="Lead_Name" HeaderText="Lead_Name" 
                SortExpression="Lead_Name" />
            <asp:BoundField DataField="Overview" HeaderText="Overview" 
                SortExpression="Overview" />
        </Columns>
        <EditRowStyle BackColor="#999999" />
        <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
        <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
        <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
        <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
        <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
        <SortedAscendingCellStyle BackColor="#E9E7E2" />
        <SortedAscendingHeaderStyle BackColor="#506C8C" />
        <SortedDescendingCellStyle BackColor="#FFFDF8" />
        <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
    </asp:GridView>
    <asp:SqlDataSource ID="ReportConn" runat="server" 
        ConnectionString="<%$ ConnectionStrings:GNSConcallReportsConnectionString %>" 
        SelectCommand="SELECT [Report_No], [Project_Name], [Start_Time], DATEDIFF(minute,[Start_Time],[End_Time]) as 'Duration (In Min)', [Engineer_Name], [Lead_Name], [Overview] FROM [ConcallReports]">
    </asp:SqlDataSource>

但是我根据我在下面的表单中使用的过滤器动态更改选择条件。

   ReportConn.SelectCommand = "SELECT [Report_No], [Project_Name], [Start_Time], DATEDIFF(minute,[Start_Time],[End_Time]) as 'Duration (In Min)', [Engineer_Name], [Lead_Name], [Overview] FROM [ConcallReports] where "+query; //Here query indicates the filter that was used
    ReportConn.DataBind();

除了排序外，上述所有工作正常。

当我进行排序时，正在进行排序。但是我丢失了过滤后的值，我得到了在页面开头加载的数据。

请帮我解决问题