php 注册有关问题 求解

php 注册问题 求解!


Notice: Undefined variable: POST in D:\www\bbs\reg.php on line 5

PHP code

<!--

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--><?php include("conn.php");
 include("head.php");
if(isset($_POST['submit'])) {
    $sql="insert into user_list(uid,username,password,email,regdate)values('','$POST[username]','$POST[password]','$POST[email]',now())";
   mysql_query($sql);
    "<script language = \"javascript\">alert('添加成功');history.go(-1)";
}
?>

用户名：
确认密码：
邮箱：

------解决方案--------------------
,'$POST[username]','$POST[password]','$POST[email]' ???

$_POST