如何将我的标记字段插入带数组的数据库？

Here is my loop but I don’t know what I should do:

$etiketler = 'tag,tag2,tag3,tag4';    
$var = $etiketler;
        foreach ($var as $e) {
        $keywords_data = array(
            'tag_name' => $e,
        );
        insert('cms_etiketler',$keywords_data);
    }

My insert function is:

function insert($table,$data) {
    global $db;
    $sql = $db->insert($table, $data);
    return $sql;
}

I’m using MySQLi db class from here: https://github.com/ajillion/PHP-MySQLi-Database-Class

How can I add these tags into my tags table one by one?

UPDATE:

I found the solution:

$var = preg_split("/[\s,]+/", $etiketler);

I found the solution:

$var = preg_split("/[\s,]+/", $etiketler);

More info : http://www.php.net/manual/en/function.preg-split.php