protected void ddlCode_SelectedIndexChanged(object sender, EventArgs e)

{

    DropDownList ddlCode = (DropDownList)sender;

    //根据现有的控件的NamingContainer获取到该控件所在的父级GridView的所在行

    GridViewRow gvr = (GridViewRow)ddlCode.NamingContainer;
　　 //根据获得的gvr使用同样的属性获得外层的GridView

    GridView gv = gvr.NamingContainer as GridView;
　　//获取gvr的行索引
　　int i_RowIndex = gvr.RowIndex;

}