PHP & MYSQL: using group by for categories

Question

My database has the following setup

productid | productname | category id

and I want to output them like so:

category #1
it         


        

Answer 1

What you want is to order them by the category, not group them.

SELECT * FROM MyTable
ORDER BY category_id, product_id

When you iterate through the list, just output a new header whenever the category_id changes.