I need help formatting a search query to exclude results found between two strings.

Specifically, I am trying to search a vBulletin database for text in posts while excluding text within quote tags. So I want don't want any results that are between "[quote" and "[/quote]".

Lets say I'm searching for "yellow". How would I format this to exclude all instances within the quote tags?

Code:
SELECT pagetext FROM post WHERE yellow
It sounds like it would be a simple and common query, but I've been searching for hours and coming up with nothing useful.