The book I am reading right now would help you out greatly. It is called PHP & Mysql novice to ninja.
First of all, you don't have to repeat the code 10 times. You need to actually use something called a placeholder. Also, you might want to configure your mysql database to have a hidden category and therefore you can hide all of the products that you don't want to show on any given page.
Thirdly, from what I gather your code could be better in the fact that it is much more safer and secure if you use prepare statements as opposed to what you are using. Finally, it is best practices that anytime you query the database to wrap your code in TRY/CATCH statements.
Here is an example:
$sql = 'SELECT id, name FROM category where id = :id'
$s = $pdo->prepare($sql);
catch (PDOException $e)
$error = 'Error removing jokes from category.';
As I see it, your most pressing concern is database design and NOT an sql statement. You must design flexibility into it.