GridView中给DropDownList动态绑定数据，及选择列表值后自动更新数据库

protected void sgvFile1_RowDataBound(object sender, GridViewRowEventArgs e)
{ 
    DropDownList ddlAM = ((DropDownList)e.Row.FindControl("ddlAM"));
    ddlAM.SelectedIndexChanged += new EventHandler(ddlAM_SelectedIndexChanged);
    ddlAM.SelectedIndex = -;
    ddlAM.Items.FindByValue(labAM.Text).Selected = true;

}

protected void ddlAM_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddlAM = (DropDownList)sender;
        string i = ddlAM.ID.Substring(ddlAM.ID.LastIndexOf("ddlAM") + , ddlAM.ID.Length - );
        bool flage = false;
        GridViewRow row = (GridViewRow)ddlAM.NamingContainer;
        Label labAMPersonID = (Label)row.FindControl("labAMPersonID" + i);

        try
        {
            UpdateKaoQin(labAMPersonID.Text, ddlAM.SelectedValue);
        }
        catch
        {
            ScriptManager.RegisterClientScriptBlock(UpdatePanel1, typeof(UpdatePanel), "result", "alert('修改失败！');", true);
        }
    }