Medical Center database
Non primary-foreign key JOINs
Non-equi JOINs
Non-equi self JOINs
Summary
25. Summary

## Instruction

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:
SELECT
car.name
JOIN car
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 BETWEEN operator:
SELECT
auctioneer.name,
item.name
FROM auctioneer
JOIN item
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.

## Exercise

Click the button to continue.

Code editor

TableConsole