preg_replace equivalent?

Is there an equivalent MySQL function to PHP’s preg_replace function?

I want to replace certain characters for comparisson.

SELECT * FROM TableName WHERE PREG_REPLACE(REGULAR_EXPRESSION_HERE, REPLACEMENT_STRING_HERE) = STRING_TO_COMPARE_WITH;

nope. regexp’s in mysql are true/false only. the only functions you have for actually modifying strings are here: http://dev.mysql.com/doc/mysql/en/string-functions.html