multiple select to mysql

HTML:
<form action="" method="post">

<select multiple="multiple" size="5" name="assign[]"> <!--把資料轉成array-->
<option value="alice">alice</option>
<option value="Jay">Jay</option>
<option value="Hoho">Hoho</option>
<option value="joan">joan</option>
</select>
<input type="submit" value="submit me!" />
</form>


PHP:
<?php
echo $_POST['assign']; //print Array;

echo $assignstr = implode (',', $_POST['assign']); //把這些資料存成字串 alice,Jay 到mysql裡

$arrUsers = Explode(",", $row_Recordset5['assignUser']); //再把資料轉回array

foreach($arrUsers as $value){
echo $value."<br/>"; //在php頁面顯示
}


?>