Appendix FULL OUTER JOIN

265. FULL OUTER JOIN

Here’s another join type to your collection: FULL OUTER JOIN. 😉

FULL OUTER JOIN returns both rows from the left and right table (if the record from one table has no matched record from the other table all columns will have NULL value).

I haven’t used FULL OUTER JOIN for a long time (read never) and it’s another one of those interview questions.

Here’s an example query that joins library entries and users:

SELECT * FROM books_users b FULL OUTER JOIN users u ON b.user_id = u.id

IMO everything could be done via INNER and LEFT joins. It’s better to...

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