This question already has an answer here:
- LEFT JOIN vs. LEFT OUTER JOIN in SQL Server 12 answers
What is the difference in results between:
- RIGHT JOIN and RIGHT OUTER JOIN
- LEFT JOIN and LEFT OUTER JOIN ?
Can you please explain it through some examples?
There is no difference between RIGHT JOIN and RIGHT OUTER JOIN. Both are the same. That is, LEFT JOIN and LEFT OUTER JOIN both are the same.
Here's a very nice Visual Explanation of joins generally by our very own Jeff Atwood. A right outer join is the same as a right join, and left join and left outer join are also the same.
What is result difference between:
RIGHT JOIN and RIGHT OUTER JOIN
No difference.
LEFT JOIN and LEFT OUTER JOIN ?
No difference.
Simply put, the OUTER keyword is optional. You can include it or omit it without affecting the resultset.
- SQL Server Forums - Differences between Left join & Left outer join
http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=53046
- LEFT JOIN vs. LEFT OUTER JOIN
http://itknowledgeexchange.techtarget.com/itanswers/left-join-vs-left-outer-join/
- PL/SQL - What is the difference between right join and right outer ...
- "Join" is union of two or more tables (entities) with all data.
- "Outer" is union of two or more tables except the attributes used for union
来源：https://stackoverflow.com/questions/3183669/difference-between-right-left-join-vs-right-left-outer-join-in-sql