SQL 中左右连接与右外连接的区别

两者的结果有何不同:

  1. 右连接和右外连接
  2. 左连接和左外连接？

你能举几个例子解释一下吗？

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最佳答案

There is no difference between RIGHT JOIN and RIGHT OUTER JOIN. Both are the same. That means that LEFT JOIN and LEFT OUTER JOIN are the same.

Visual Representation of SQL Joins

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Here's a very nice Visual Explanation of joins generally by our very own Jeff Atwood. A right outer join is the same as a right join, and left join and left outer join are also the same.

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What is result difference between:

RIGHT JOIN and RIGHT OUTER JOIN

No difference.

LEFT JOIN and LEFT OUTER JOIN ?

No difference.

Simply put, the OUTER keyword is optional. You can include it or omit it without affecting the resultset.

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Nice explanation of SQL Join:

enter image description here

Reference: link


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