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SQL joins cheatsheet

 3 years ago
source link: https://devhints.io/sql-join
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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

SELECT * FROM `A` INNER JOIN `B`

┌────────┐
│ A  ┌───┼────┐
│    │ ∩ │    │
└────┼───┘  B │
     └────────┘
Inner join ∩ Left outer join A + ∩ Right outer join ∩ + B Full outer join A + ∩ + B

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