Search a couple tables

Hi,

i have a little search engine running. Its one table, i have a couple categories. I realized the categories with simply one field called categorie so i can show all the data in a single categorie by selecting it with the query SELECT * FROM table WHERE categorie = 'categoriename'. This works quite fine. But now i read my new book. Its MySQL and mSQL by OReilly. Its a very great book. According to their database design chapter its better if i would create one table for each categorie. That would be no problem but: How am I gonna search more then one table with one query? Some say I can do this with Joins but i dont know how. Can somebody help me??

I haven't tested the follow code but i think that it work!

The query you search:
$query = "SELECT t1.*,t2.*,t3.* FROM table1 as t1, table2 as t2, table3 as t3 WHERE t1.categorie='categoriename' or t2.categorie='categoriename' or t3.categorie='categoriename'";

Please tellme if this statement works! Thanx!