php正则表达式匹配撇号内的所有文本

Here is the string: WHERE CLASS = 'CARL-01' OR CLASS = 'CARL-03' OR CLASS = 'CARL-04' OR CLASS =''

I need a regex function that will match the below probably using preg_match via php:

CARL-01
CARL-03
CARL-04

Any ideas?

preg_match_all('/\'([^\']+)\'/', $string, $matches);
$matches = $matches[1];