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Oracle:SELECT * FROM tablea a,tableb b WHERE a.fielda(+)= b.fieldb - 什么是(+)?

[英]Oracle: SELECT * FROM tablea a, tableb b WHERE a.fielda(+)=b.fieldb — what is (+)?

I cannot understand what the role of the (+) is! 我无法理解(+)的作用是什么! (I "inherited" the statement through the automated update process of an application I am maintaining at the moment). (我通过我目前维护的应用程序的自动更新过程“继承”了该语句)。

Is this some Oracle-specific operator? 这是一些特定于Oracle的运营商吗? Does it have a special name that I can search for? 它有一个我可以搜索的特殊名称吗? It's kind of hard to google for a plus sign between brackets :) 有点难以谷歌在括号之间的加号:)

它是一个外连接运算符(old-school)。

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