What you need is a table in the middle somewhere. So you have for example CAR and PRODUCT, in the middle you need soemthing like CAR_PRODUCT.
On the tables you have some sort of ID so for cars you have CAR_ID and product you have PRODUCT_ID, the CAR_PRODUCT table holds both of these values.
So if you want to see all of the cars which have a particular product you use...
SELECT c.car_id, c.name FROM car c JOIN car_product p ON c.car_id = p.car_id
AND p.product_id = '12345';
...and if you want to see all products for a particular car use...
SELECT p.product_id, p.name FROM product p JOIN car_product c ON p.product_id = c.product_id
AND p.car_id = '12345';
Andrew Gilfrin
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