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Starting
with Oracle9i, the confusing outer join
syntax using the ‘(+)’ notation has been
superseded by ISO 99 outer join syntax.
As we know, there are three types of outer
joins, left, right, and full outer join.
The purpose of an outer join is to include
non-matching rows, and the outer join
returns these missing columns as NULL
values.
Let’s review
the syntax differences between these
variations in join syntax:
Left outer
join: Oracle8i
select
last_name,
department_name
from
employees e,
departments d
where
e.department_id = d.department_id(+);
Left outer
join: Oracle9i
select
last_name,
department_name
from
employees e
left
outer join
departments d
on
e.department_id = d.department_id; |
