How to get field value of selected Row Devexpress GridView?

I use a DevexpressGridView to display all TOPIC (id,title,content)

<dx:ASPxGridView ID="gv" runat="server"
OnSelectionChanged="gv_SelectionChanged" >

I have grid_SelectionChanged event:

protected void gv_SelectionChanged(object sender, EventArgs e)
    {

        int id= selected row...???; //how can I get the value of selected row
        string sql = "select * from TOPIC where idTOPIC="+id;
        DataTable topic = l.EXECUTEQUERYSQL(sql);
        TextBox1.Text = topic.Rows[0][1].ToString();
    }

...

It seems gv.SelectedRow method isn't exist in DevGridview.

As recommended, I've tried with FocusedRowIndex method, but I really dont know the right syntax to get the value of selected row.

Help!!!

Solution

I've found my answere here after a long time searching google: http://www.devexpress.com/Support/Center/Question/Details/Q347704

Use the ASPxGridView.GetSelectedFieldValues method get selected row values on the server side.