select with multiple AND and OR attributes

[SilverRain]

I am trying to do something fairly simple.

I have two pages. Brands.php and Products.php.

When I click on Brands.php it takes me to a list of Brands. I click on a brand, for example, brand1.php. From there I can choose a category - Category1.

Category1 needs to go to store.php?BrandID=1&CatID=1. At this point I have only got it to filter by either or... either BrandID or CatID. So I go to store.php?BrandID=1, I get all items that are under Brand1, and similarly, when I go to CatID=1, I get all items that are under category1.

The problem is that I cannot get it to filter by BrandID and CatID together. I need something of a combination of the AND/OR fuction in SQL.

At this point here is what I have:

SELECT *
FROM products
WHERE BrandID = colname OR CatID = colname2

I have two variables defined: colname and colname2.

Name: colname
Type: Numeric
Default value: -1
Run-time Value: $_GET['BrandID']

Name: colname2
Type: Numeric
Default value: -1
Run-time Value: $_GET['CatID']


This is successfully doing what I have described above, but I need it to filter by each one individually AND both together.

I have tried:

SELECT *
FROM products
WHERE (BrandID = colname OR CatID = colname2) OR (BrandID= colname AND CatID = colname2)

but it did not succeed. Do I need to add a new colname3, perhaps?

I am using Dreamweaver's Advanced Recordset.

Your help and detailed answer will be greatly appreciated!

Thanks!

[ronverdonk]

I would like to know what is the reasoning behind such a select. Because I cannot see any meaning in this.

this second part of the where clause is completely unnecessary;

BrandID= colname AND CatID = colname2)

because the result is already determined by the first part of the WHERE clause.

Maybe I don't understand it. In that case would you please explain why you would want and how you would use thee results of such a select.

Ronald