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Say NO to Venn Diagrams When Explaining JOINs
- 1_player 10y agoNonsense. 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/Visual_SQL_JOINS_orig.jpg http://www.codeproject.com/KB/database/Visual_SQL_Joins/Visu...
- chris_wot 10y agoThey 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.