outer table...where...和left join table on ...有什么区别?

wangfred1 发表于 2006-01-09 17:09

RT.

xxyyy 发表于 2006-01-09 19:27

不知，帮你顶

IFMXDBA 发表于 2006-01-09 23:24

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in my opinion, no difference. Informix introduced the left outer, righer outer join in 9.4 as a compensation of ANSI join.The normal join in Informix ( not the outer join ) was known as "natural join" in RDBMS theory. You can implement any join by just normal join, outer join ( left outer or right outer, either is fine ) and Union operation.Just like you can go any where, if you can do "go direct" and "trun right".

qza 发表于 2010-06-02 15:44

outer可对where中的条件再次过滤，而left outer join 仅对on条件有效，如果不满足on条件，则直接提取左表数据，右表置空，而对其它附加的条件不再做判断了

qza 发表于 2010-06-02 15:45

我的环境sco506,informix online731环境是这样的

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outer table...where...和left join table on ...有什么区别?

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