I have several tables in a MySql database.

I have a classifieds website, and at the bottom I display the users last visited classifieds. I do this by storing the ID:s of the ads to an array in the cookie.

Now, my db is made up like this kindof:

     Main Table: // Stores global information, ie these fields have to be filled out in every record, never be blank
       ID
       Price
       category
       Seller

    Item Table: // Stores descriptive info about whats for sale
      ID
      AD_ID (FK) //This is the same as ID in the MAIN TABLE
      Color
      Size
      Mileage etc

My problem is that I need to know what category the ad is in, in order to query mysql for the right information I think.

So I need two variables, but the cookie only has one (ID) stored.

Offcourse I could make two queries, first one just matching the ID to the main_table and fetch the category from the Main_table. Then make the second query and fetch all other info from the right table.

Here is an example if the category was Vehicles:

SELECT * FROM main_table, vehicles_table, WHERE main_table.id=$id_from_cookie AND main_table.ad_id=vehicles_table.ad_id

As you can see above, I need the category to write in what table to check, right?

But I think there must be a smarter way, like fetching them in one single query using only one variable (id from cookie)? How should I do this?

Understand?

Let me know if you need more input...

Thanks