Translate using array_slice!?

I have a page where I have all the language saved in a mysql db. Now I want to create a script so I can translate the page to different languages in a easy way. Everything written on my page is generated by language snippets like this:

<? echo ''._TOOLBAR_ADDLINK_TEXT_HEADER.''; ?>

Code (markup):

It reffers to a page with the refering line like this:

define("_TOOLBAR_ADDLINK_TEXT_HEADER","Welcome to the ToolBar");

Code (markup):

This page is generated from mysql like this:

$sql = mysql_query("SELECT * FROM ".$prefix."_lang_code WHERE lang_id = '1'");
while($row = mysql_fetch_array($sql)) {
                define("_".$row['tagname']."","".$row['string']."");
}

Code (markup):

Now what I want is an easy way to translate this, and I thourgt I would do it like this:

$langs = array();
$langs[2] = array();
$sql = mysql_query("SELECT * FROM ".$prefix."_lang_code WHERE lang_id = '1'");
while($row = mysql_fetch_array($sql)) {
	$langs[$row['lang_id']][] = $row['tagname'];
}

$sql = mysql_query("SELECT * FROM ".$prefix."_lang_code WHERE lang_id = '2'");
while($row = mysql_fetch_array($sql)) {
	if(!in_array($row['tagname'], $langs['2'])) {
		$edit[] = $row;
	}
}

echo "Still needs to be translated: ".count($edit);

$slice = array_slice($edit, 0, 1);

Code (markup):

Now this should give the benefit, that if new tagnames is added I would be able to see it in this script and then translate, but...

I keep getting this error:

Warning: array_slice() expects parameter 1 to be array, null given in /home/mypage/public_html/admin/translate.php on line 71

I can't figure out where it goes wrong.

I have these fields in my DB:

id
lang_id
tagname
string

Can somebody please help!!!

 

$edit is null in case nothing needs to be translated. So a $edit = array() before any if-statements.

Also.. why would you run both SQL SELECT queries when you only need one? Choose which language to use first (based on subdomain/cookie/whatever), then do a switch/case to run only the necessary query which fills your array.