21 lines
329 B
Markdown
21 lines
329 B
Markdown
---
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title: SQL Join
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---
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```
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SELECT * FROM order_items LEFT OUTER JOIN orders ON order_items.order_id = orders.id
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```
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```
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.--------.
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| A .---+----.
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| | ∩ | |
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'----+---' B |
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'--------'
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```
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* inner join = `∩`
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* left outer join = `A` + `∩`
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* right outer join = `∩` + `B`
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* full outer join = `A` + `∩` + `B`
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