这些是同义词。



见 http://technet.microsoft.com/en-us/library/ms187518（ v = sql.105）.aspx [ ^ ]

These are synonyms.

See http://technet.microsoft.com/en-us/library/ms187518(v=sql.105).aspx[^]

SQL服务器对FROM子句中指定的外连接使用以下ISO关键字：

• LEFT OUTER JOIN或LEFT JOIN
• RIGHT OUTER JOIN或RIGHT JOIN
• FULL OUTER JOIN或FULL JOIN

SQL Server uses the following ISO keywords for outer joins specified in a FROM clause:


• LEFT OUTER JOIN or LEFT JOIN
• RIGHT OUTER JOIN or RIGHT JOIN
• FULL OUTER JOIN or FULL JOIN





来源：使用外部联接 [ ^ ]



LEFT JOIN 和 LEFT OUTER JOIN 与MS SQL服务器具有相同的含义。



这是一篇关于连接的优秀文章： SQL连接的可视化表示 [ ^ ]，它可以帮助你理解它是如何工作的！



source: Using Outer Joins[^]

LEFT JOIN and LEFT OUTER JOIN has the same meaning to MS SQL server.

Here is an excellent article about joins: Visual Representation of SQL Joins[^] which ight help you to understand how it works!




绝对没有LEFT JOIN和LEFT OUTER JOIN之间的区别。对于RIGHT JOIN和RIGHT OUTER JOIN也是如此。在SQL Server中使用LEFT JOIN关键字时，它仅表示LEFT OUTER JOIN。





两者都相同。 OUTER这个词是可选的



请参考： -

http://blog.sqlauthority.com/2009/04/13/sql-server-introduction-to-joins-basic- of-joins / [ ^ ]

There is absolutely no difference between LEFT JOIN and LEFT OUTER JOIN. The same is true for RIGHT JOIN and RIGHT OUTER JOIN. When you use LEFT JOIN keyword in SQL Server, it means LEFT OUTER JOIN only.


Both are same. The word OUTER is optional

refer this:-
http://blog.sqlauthority.com/2009/04/13/sql-server-introduction-to-joins-basic-of-joins/[^]