SQL "*=" operator [duplicate]

This question already has answers here: Closed 13 years ago.

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Transact-SQL shorthand join syntax?

I ran across a T-SQL script that does someth开发者_运维百科ing like this in the where clause:

...
where o.obj_code *= c.prv_code

I can't seem to find any documentation on the *= operator. Can anyone explain its use and maybe point to some documentation on it? Is this specific to T-SQL?

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Deprecated Outer Join syntax.
In on the list of Deprecated Engine Features:

Use of *= and =*
Use ANSI join syntax. For more information, see FROM (Transact-SQL).

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It's an old way to do outer joins. Here's an article that explains in more detail.

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It is old non-ANSI outer join syntax. Don't use it. Heres and MSDN reference.

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*= is an old way to do left outer joins that came from Oracle. I found a mention to it in the SQL Server docs once as something they highly recommended not doing.

Here's some info on it from MS:

Transact-SQL Joins

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That's the old syntax for a left outer join, and was deprecated from SQL Server 2005 upwards.