'LEFT JOIN' vs 'LEFT OUTER JOIN'

最后都变了- 提交于 2019-12-05 18:23:15

[OUTER] is optional, per the ANSI spec (92, but I'm sure later versions also cover it).

Of course, you're assuming that every SQL product is ANSI compatible. For joins, they probably are..

ANSI JOINS

http://www.oratechinfo.co.uk/ansi_joins.html

Note, the OUTER can be dropped, since, by definition, LEFT, RIGHT and FULL JOINs MUST be OUTER joins (it's down to personal preference and readability)

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