如何在GridView控件中添加自动编号的功能?

放一段参考代码,提醒自己.

---

public partial class DataGrid_1 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string strConn = System.Configuration.ConfigurationManager.AppSettings["sqlConnectionStringusertest"];

        SqlConnection conn = new SqlConnection(strConn);
        try
        {
            conn.Open();
            string strda = "select name,nick,pwd,info from guest";
            SqlDataAdapter da = new SqlDataAdapter(strda,conn);
            DataSet ds = new DataSet();
            da.Fill(ds,"testTable");
            GridView1.DataSource=ds.Tables[0];
            GridView1.DataBind();

           
        }
        catch (Exception error)
        {
            Response.Write(error.Message.ToString());
        }
    }
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        //如果当前项不为空
        if (e.Row.RowIndex!=-1)
        {
           //取得当前索引项的值加一
            int _ID = Convert.ToInt32(e.Row.RowIndex)+1;
            //设置第一列的单元格的内容为当前索引值+1
            e.Row.Cells[0].Text = _ID.ToString();

        }
    }
}