php 注册有关问题 求解

php 注册问题 求解!


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PHP code

<?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)</script>";}?><form action="reg.php" method="post">用户名：    <input type="text" name="username" /><br>确认密码：  <input type="password" name="password" /><br>邮箱：  <input type="text" name="email" /><br>  <input type="submit" name="submit" value="注  册"/>  <input type="reset" name="reset" value="重  置"/>  </form>