Alright! Let's summarize everything we learned in this part.
- We don't have to join tables on the primary-foreign key relationship. It is possible to use any two columns:
ON owner.preferred_car_type = car.type
The query above will show the name of every buyer together with every car that matches their preferred type.
- We also don't have to use the equality operator when joining tables. We are free to use other comparison operators (
<>) or the
ON auctioneer.funds > item.price
- We can write a special kind of
JOIN to list items within a certain range (for example, within a budget), all pairs of items, or all unique pairs.