Why can't I convert the value of a regular match to uppercase?

Why can't I capitalize on a regular matching value?

function Syntax_color_sql ($string)
{
$pattern = ' #select |left join|having|union|from|right join|limit|where|order by|for Lock#sui ';
Return Preg_replace ($pattern, ". Strtoupper (' $"). ", $string);
}

------Solution--------------------
This post was last edited by xuzuning on 2013-01-25 12:38:54

$pattern = ' #select
------Solution--------------------
Left Join
------Solution--------------------
Having
------Solution--------------------
Union
------Solution--------------------
From
------Solution--------------------
Right Join
------Solution--------------------
Limit
------Solution--------------------
where
------Solution--------------------
ORDER BY
------Solution--------------------
For Lock#sui e';
Return Preg_replace ($pattern, ' "" . Strtoupper ("$"). ""', $string);

