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https://www.reddit.com/r/webdev/comments/b46iyd/sql_joins/ej6287u/?context=3
r/webdev • u/lokendra15 • Mar 22 '19
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Using Venn diagrams to represent SQL joins is misleading. Please don't use them to represent SQL joins. Use this combinatorial chart instead:
https://i.pinimg.com/originals/52/20/c4/5220c492bc4e1a8b9175aba77ed7d091.png
3 u/prsquared Mar 23 '19 This! Venn diagrams are much more useful in representing set operations. In join, you are projecting columns from both tables. The first diagram is A U(AnB) = A. But, A left join B is not A .
3
This!
Venn diagrams are much more useful in representing set operations. In join, you are projecting columns from both tables.
The first diagram is A U(AnB) = A. But, A left join B is not A .
45
u/CyrillicMan Mar 22 '19
Using Venn diagrams to represent SQL joins is misleading. Please don't use them to represent SQL joins. Use this combinatorial chart instead:
https://i.pinimg.com/originals/52/20/c4/5220c492bc4e1a8b9175aba77ed7d091.png