PHP Bulk Delete Data _php tips

Bulk Delete Article this technology is not inscrutable, just want to write down to share with you. (For Beginners:)
1, first in the article List page (list.php), will select the basket named: "$del _id[]", the value is the article ID number.
For example (list.php):
<form name= "Del_form" action= "del.php" method= "POST" >
<?php
$result =mysql_query ("SELECT * from News");
while ($rs =mysql_fetch_array ($result)) {
?>
<input name= "del_id[]" type= "checkbox" id= "del_id[]" value= "<?= $rs [id]?>"/><?= $rs [title]?>
<?php
}
?>
</form>
2, processing page (del.php):
<?php
if ($del _id!= "") {
$del _num=count ($del _id);
for ($i =0; $i < $del _num; $i + +) {
mysql_query ("Delete from News where id= ' $del _id[$i]");
}
Echo ("<script type= ' Text/javascript ' >alert" (' Delete succeeded!) '); History.back ();</script> ");
}else{
Echo ("<script type= ' Text/javascript" >alert) (' Please select the item first! '); History.back ();</script> ");
}
?>