右联接等于左联接? [英] right join equal to left join?

问题描述

一段时间以来，我一直只知道如何使用INNER JOIN，而对LEFT/RIGHT(OUTER)JOIN的功能完全不了解.虽然，正如我刚刚读到的，我看不到权利"的目的是什么?

For some time I have only been knowing how to use the INNER JOIN and absolutely no clue about what LEFT/RIGHT (OUTER) JOIN does. Although, as I just read about it, I cannot see what purpose the RIGHT has?

在我看来，这与反向LEFT JOIN相同

It seems to me it's identical to a reverse LEFT JOIN

如果我们按照我的示例进行操作:

If we follow my example:

SELECT t1.* FROM table1 t1 RIGHT JOIN table2 t2 ON t2.value = t1.value

将等同于:

SELECT t2.* FROM table2 t2 LEFT JOIN table1 t1 ON t1.value = t2.value

这是对的，还是我错过了一些东西?

Is this right, or am I missing something out?

推荐答案

是的，您可以通过搜索以下内容找到更多信息:

Yes this is right, you can find more information if you searched:

SQL中的左联接和右联接之间的差异服务器

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