What is the difference between LEFT JOIN
and LEFT OUTER JOIN
?
SQL Server LEFT JOIN vs LEFT OUTER JOIN – Differences Explained
left-joinouter-joinsql-servert-sql
left-joinouter-joinsql-servert-sql
What is the difference between LEFT JOIN
and LEFT OUTER JOIN
?
Best Answer
As per the documentation: FROM (Transact-SQL):
The keyword
OUTER
is marked as optional (enclosed in square brackets). In this specific case, whether you specifyOUTER
or not makes no difference. Note that while the other elements of the join clause is also marked as optional, leaving them out will make a difference.For instance, the entire type-part of the
JOIN
clause is optional, in which case the default isINNER
if you just specifyJOIN
. In other words, this is legal:Here's a list of equivalent syntaxes:
Also take a look at the answer I left on this other SO question: SQL left join vs multiple tables on FROM line?.