PHP 업로드 파일 삭제하기

$sql="select * from board where uid='$uid'";
$result=mysql_query($sql,$conn);
$row=mysql_fetch_array($result);
$del_file="/upload_file/".$row[file];
if($row[file] &&is_file($del_file)) unlink($del_file);
$sqldel="delete from board where uid='$uid'";
mysql_query($sqldel,$conn);