Why SQL inner join is called as Inner and Outer Join called as Outer?

Question

Why SQL Join named as inner and outer? what is the reason behind this?

this question was asked to me in an interview...

https://stackoverflow.com/questions/27211638/why-is-inner-join-and-outer-join-so-called — Raghavan, Aug 19 '19 at 10:31
Think Venn Diagrams and set theory. There's a fairly [decent explanation here](https://www.diffen.com/difference/Inner_Join_vs_Outer_Join), and a quick search brought up lots more — Diado, Aug 19 '19 at 10:32

score 2 · Answer 1 · answered Aug 19 '19 at 10:34

2

There are several explanations online, here is one. Inner is what matches both left and right side (inside both). Left/right mathces only that part:

answered Aug 19 '19 at 10:34

SAS

3,943
2
27
48

score 1 · Answer 2 · answered Aug 19 '19 at 10:37

1

When two tables are laid over top of each other on information that intersects, returning only the information “inside” the intersection is the INNER and returning all of the information is the OUTER.

answered Aug 19 '19 at 10:37

Mukesh Prajapat

51
2

Why SQL inner join is called as Inner and Outer Join called as Outer?

2 Answers2