求教,为什么会出现这种错误.
<?
if($_POST['action']=="add" && $_POST['category_title']!="")
{
$category_title=$_POST['category_title'];
$exec="insert into Admin_Flag_Category(category_title,puttime) values ('".$category_title."',now())";
mysql_query($exec);
}
?>
提示错误为:Notice: Undefined index: action in /stg_web/dd@manage.nn/admin/Admin_List.php on line 7
请高手帮帮忙啊!