MySQL wp_query help

I would like some help in creating a SQL statement that will query my WordPress database and return results based on search terms a user enters.

Basically it would be like this.

User term 1 (general string)
User term 2 (zip code)

Return results if general string and/or zip code is found in either the title, description of the post, or the category of the post.

The hard part (for me) is getting the category part.

My guess is that it would be a simple SELECT statement with an INNER JOIN, but I my SQL skills are very limited.

Any help would be greatly appreciated.