Outer join is like this:

There are two sets of datas namely A and B.

Union is to join two sets together.
A + B (A U B)

Intersect is to find the common datas in both sets A & B
A ^ B

Outer join is Union both sets excluding Intersection.


i.e A is student, B is Teacher.

Union, Find all people are students or Teacher.

Intersect, Find all people are students and Teachers.

Outer Join, Find all people are students but not teachers
and all people are teachers but not students.

See!

g2david
:-)