Natural Join Venn Diagram

Most venn diagrams associated with joins on stack overflow are parroted worthless misrepresentations even in cases where a venn diagram could be useful.

Natural join venn diagram. Although venn diagrams are unsuitable for explaining inner join one diagram under a suitable interpretation is useful for comparing inner left outer right outer full outer join. A venn diagram consists of multiple overlapping closed curves usually circles each representing a set. I thought ligaya turmelle s post on sql joins was a great primer for novice developers. 11 oct 2007 a visual explanation of sql joins.

A venn diagram also called primary diagram set diagram or logic diagram is a diagram that shows all possible logical relations between a finite collection of different sets these diagrams depict elements as points in the plane and sets as regions inside closed curves. Since sql joins appear to be set based the use of venn diagrams to explain them seems at first blush to be a natural fit. A visual explanation of sql joins coding horror i thought li a turmelle s post on sql joins was a great primer for novice developers since sql joins appear to be set based the use of venn diagrams to say no to venn diagrams when explaining joins java sql in recent times there have been a couple of tremendously popular blog posts explaining joins using venn diagrams after. A left and right circle that are the tuples returned from left and right outer joins respectively.

However like the commenters to her post i found that the venn diagrams didn t quite match the sql join syntax reality in my testing.