How to delete uploaded files in php

<?php
/* 图片删除处理页 */
if($_GET["p_url"])
{
$purl = $_GET["p_url"];    //获取文件保存路径
$file_delete = "../".$purl;    //根据自己的文件目录设置路径信息
$str = "DELETE FROM picture WHERE p_url=&#39;".$purl."&#39;";    //从数据库中删除图片文件
$delete = mysql_query($str);
if($delete)
{
unlink($file_delete);    //从自己写入的路径删除图片文件
echo "<script>alert(&#39;图片信息删除成功！&#39;);window.location.href=&#39;picture_manage.php&#39;</script>";
}
else
{
//echo $str;
echo "<script>alert(&#39;图片信息删除失败！&#39;);window.location.href=&#39;picture_manage.php&#39;</script>";
}
}
else
{
echo "<script>alert(&#39;请选择要删除的图片信息！&#39;);window.location.href=&#39;picture_manage.php&#39;</script>";
}
?>