How to JOIN tables?

I have two tables.

Table one had a column with category numbers in the following format:

t1.cat = 2,55,67,34

I also have another table with id column, where column ID is one of those numbers in t1.cat

t2.ID
t2.description

How do I join t2 to a query on t1 so that I could output t2.description if t2.ID found in t1.cat cell?

INNER JOIN t2 ON ( t2.ID = t1.cat)

???????????

Create a third table with the cat numbers and a link back to t1. Trying to store an array in a row (as you have with t1) is a common mistake.

The word "relational" in Relational Data Base Management System gives you tremendous power and flexibility.

create table t3 as (
t1_id int;
cat int)

At this stage I can not add tables. Is there a way to join tables with what I've got?

You should be able to join them using a regular expression.

http://dev.mysql.com/doc/refman/5.0/en/regexp.html

I have MySQL 3.23.58, and this looks like something for v.5...

This is working on mysql 4.1, but I dont know about mysql 3.23 ...

SELECT 
	t2.ID, t2.description
FROM `table_2` t2, `table_1` t1
WHERE t1.cat REGEXP '(^|,)'+t2.ID+'(,|$)'