Unless I misunderstand the desired result, this query would be better formulated
using 2 left joins instead, like this:
SELECT ...
FROM Persons LEFT JOIN Pets ... LEFT JOIN PetAccessories ...
-- Darren Duncan
On 2017-03-22 2:22 AM, Chris Locke wrote:
An interesting discussion of it on StackOverflow...
http://stackoverflow.com/questions/689963/does-anyone-use-right-outer-joins
To give one example where a RIGHT JOIN may be useful.
Suppose that there are three tables for People, Pets, and Pet Accessories.
People may optionally have pets and these pets may optionally have
accessories.
If the requirement is to get a result listing all people irrespective of
whether or not they own a pet and information about any pets they own that
also have accessories.
All in all probably easiest to use a RIGHT JOIN
SELECT P.PersonName,
Pt.PetName,
Pa.AccessoryName
FROM Pets Pt
JOIN PetAccessories Pa
ON Pt.PetName = Pa.PetName
RIGHT JOIN Persons P
ON P.PersonName = Pt.PersonName;
Though if determined to avoid this another option would be to introduce a
derived table that can be left joined to.
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