This sample regexp may be useful if you are working with DB field types. 

(?P<type>\w+)($|\((?P<length>(\d+|(.*)))\))

For example, if you are have a such type as "varchar(255)" or "text", the next fragment

<?php
   $type = 'varchar(255)';  // type of field
   preg_match('/(?P<type>\w+)($|\((?P<length>(\d+|(.*)))\))/', $type, $field);
   print_r($field);
?>

will output something like this:
Array ( [0] => varchar(255) [type] => varchar [1] => varchar [2] => (255) [length] => 255 [3] => 255 [4] => 255 )