SQL joins
A cheatsheet by @rstacruz|Refreshed 7 months ago.Refresh|View source on Github

Example

Example

SELECT * FROM order_items \
  LEFT OUTER JOIN orders \
  ON order_items.order_id = orders.id

Joins are typically added to SELECT statements to add more columns and records.

Diagram

Diagram

SELECT * FROM `A` INNER JOIN `B`
┌────────┐
│ A  ┌───┼────┐
│    │ ∩ │    │
└────┼───┘  B │
     └────────┘
Join What
Inner join
Left outer join A +
Right outer join + B
Full outer join A + + B