I need to extract everything after the last \'=\' (http://www.domain.com?query=blablabla - > blablabla) but this query returns the entire strings. Where did I go wrong in here:<
Try this (it should work if there are multiple '=' characters in the string):
SELECT RIGHT(supplier_reference, (CHARINDEX('=',REVERSE(supplier_reference),0))-1) FROM ps_product