
Say NO to Venn Diagrams When Explaining JOINs - mikecarlton
https://blog.jooq.org/2016/07/05/say-no-to-venn-diagrams-when-explaining-joins/
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1_player
Nonsense. Venn diagrams might be incorrect to explain joins, but ever since
I've seen this image[α] 10+ years ago, that's what I think of _every single
time_ I'm writing one.

Mnemonic > Correct.

[α]
[http://www.codeproject.com/KB/database/Visual_SQL_Joins/Visu...](http://www.codeproject.com/KB/database/Visual_SQL_Joins/Visual_SQL_JOINS_orig.jpg)

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chris_wot
They don't show the projection, and I think it is far better to introduce
those working with joins to projections, selections and the algebraic notion
of a join.

