Question : MYSQL SELECT based on criteria from a second table

Here's the mess I got myself into:

I set up products table like this

id  |  category  |  etc
1       4
2       2
.
.
.


categories table like this

id  |  category  |  sub_category  |  description  |  etc
1      hinges        clip-on
2      hinges        compact
3      plates         clip-on
.
.
.

This has worked for most situations far because I usually have the sub_category id handy before doing a product query. I am only now realizing that I don't have the knowledge of how to write a query that will select something based on the "primary" category without doing two separate queries and a lot of php :(

For example: if I want products from category 'hinges' I need a way of having the query select 1 AND 2 from the products table.

I'm kind of new at this. I'm not very good with JOINs but I feel like that might be part of the solution?

Also I'm trying to do this the "dry" way...but someone let me know if I'm on the wrong path altogether!!

Thanks in advance!

Answer : MYSQL SELECT based on criteria from a second table

SELECT a.*, b.* FROM products as a, category as b WHERE b.category='hinges' AND a.id = b.id