Dynamic sort for a GridView

Here is a sample to pass column variables to control SORT ORDER:

<asp:GridView ID=”GridView1″ runat=”server” AutoGenerateColumns=”False”  
            DataSourceID=”SqlDataSource1″> 
            <Columns> 
                <asp:BoundField DataField=”Item” HeaderText=”Item” SortExpression=”Item” /> 
                <asp:BoundField DataField=”Category” HeaderText=”Category”  
                    SortExpression=”Category” /> 
                <asp:BoundField DataField=”id” HeaderText=”id” SortExpression=”id” /> 
            </Columns> 
        </asp:GridView> 
        <asp:SqlDataSource ID=”SqlDataSource1″ runat=”server”  
            ConnectionString=”<%$ ConnectionStrings:mytest1ConnectionString %>” > 
           
        </asp:SqlDataSource> 
        <asp:Button ID=”Button1″ runat=”server” onclick=”Button1_Click” Text=”Sort” /> 
         <asp:Button ID=”Button2″ runat=”server” onclick=”Button2_Click” Text=”ReverseSort” /> 
 
 
protected void Page_Load(object sender, EventArgs e) 
        { 
            if (!IsPostBack) 
            { 
                SqlDataSource1.SelectCommand = “SELECT id, Item, Category FROM Items order by id desc”; 
                GridView1.DataBind(); 
            } 
        } 
 
        protected void Button1_Click(object sender, EventArgs e) 
        { 
            string sortBySelected = “Item”;  
            string sortBySelected2 = “Category”; 
           
            SqlDataSource1.SelectCommand = “SELECT id,Item, Category FROM Items ORDER BY CASE WHEN @sortBySelected = ‘Item’ THEN Item END, CASE WHEN @sortBySelected2 = ‘Category’ THEN Category END”; 
            SqlDataSource1.SelectParameters.Clear(); 
            SqlDataSource1.SelectParameters.Add(“sortBySelected”, sortBySelected); 
            SqlDataSource1.SelectParameters.Add(“sortBySelected2″, sortBySelected2); 
                       
            GridView1.DataBind(); 
        } 
 
        protected void Button2_Click(object sender, EventArgs e) 
        { 
            string sortBySelected = “Item”; 
            string sortBySelected2 = “Category”; 
 
            SqlDataSource1.SelectCommand = “SELECT id,Item, Category FROM Items ORDER BY CASE WHEN @sortBySelected = ‘Item’ THEN Item END DESC, CASE WHEN @sortBySelected2 = ‘Category’ THEN Category END DESC”; 
            SqlDataSource1.SelectParameters.Clear(); 
            SqlDataSource1.SelectParameters.Add(“sortBySelected”, sortBySelected); 
            SqlDataSource1.SelectParameters.Add(“sortBySelected2″, sortBySelected2); 
 
        } 
    }