SQL Multiply Equals (*=) in a WHERE clause

Question

I just saw the weirdest thing ever in some very old SQL code we have.

There is a multiply equals operator in a where clause. Does it have a special meaning? It selects the appropriate columns, but o.name is NULL.

I am sure it is a typo, but I just want to confirm.

select  c.name,
        c.status,
        o.name
from    syscolumns c,
        sysobjects o
where   c.id = object_id('dbo.MyTable')
and     c.cdefault *= o.id
order by colid asc

Sorry about the duplicate question. It's really hard to google for special characters like "*=" — Peet Brits, Mar 25 '14 at 12:55
Searching for "*=" (in quotes) works on SO but not on google. I will try it next time. — Peet Brits, Mar 25 '14 at 13:06

score 0 · Accepted Answer · edited May 23 '17 at 10:31

0

This question was already answered here: SQL Server *= Operator?

Beyond being the oldschool way, as fancyPants mentioned, it also may not always work consistently. You should revise your SQL statement to include the JOINS in the FROM clause.

To answer your question: *= is a LEFT OUTER JOIN, while =* is a RIGHT OUTER JOIN

edited May 23 '17 at 10:31

Community

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answered Mar 25 '14 at 12:51

Jem

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score 0 · Answer 2 · answered Mar 25 '14 at 12:51

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As mentioned, this is a LEFT OUTER JOIN. Similarly, =* is a RIGHT OUTER JOIN

That said, it shouldn't be used anymore, and you should use the full syntax.

answered Mar 25 '14 at 12:51

Tom

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score 0 · Answer 3 · answered Mar 25 '14 at 12:52

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*= (LEFT OUTER JOIN)

=* (RIGHT OUTER JOIN)

answered Mar 25 '14 at 12:52

Flavia Obreja

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SQL Multiply Equals (*=) in a WHERE clause

3 Answers3