Question

I have a query that I pulled from ms sql 2000 and plugged into a MySql query. It did not work, MySql would choke on the *= operator. In this example I have two varchar columns called person_name.

SELECT * FROM tbl1 a, tbl2 b 
WHERE a.id = b.id
AND a.person_name *= b.person_name

I know in other languages myInt *= myTotal could also be read as myInt * myInt = myTotal. However, I’m working with varchars that contain all chars, no integers. I wrote it out like:

AND a.person_name * a.person_name = b.person_name

Voila! It appears to have worked. Can somebody explain what is happening? Is the *= operator converting the chars to their integer equivalents or? And why couldn’t I find this operator anywhere on the web?

Answer 1

In SQL 2000 this was used as a LEFT OUTER JOIN

=* is a RIGHT OUTER JOIN

Your query could be:

SELECT 
  * 
FROM 
  tbl1 a LEFT OUTER JOIN tbl2 b ON a.person_name = b.person_name
WHERE 
  a.id = b.id

As stated here:

Specifies an outer join using the
nonstandard product-specific syntax
and the WHERE clause. The *= operator
is used to specify a left outer join
and the =* operator is used to specify
a right outer join.