So this is a "feature"!  (Still a trap, though.) And I should add a disclaimer - I found this bug in a system I inherited.  I didn't write it!  I hate...

Thanks everyone.  I confirmed that aliasing the subquery in the WHERE clause does raise an error, and no rows are deleted.  I also confirmed that replacing the WHERE clause with a join...

Tested on SQL Server 2000 on two different machines, one running SP2 and the other running SP3.

good idea, thanks

Sorry, I don't have a URL for this. One of our DBAs called MS about 6 wks. ago after we had were unable to troubleshoot this problem. She got...

Forgot to mention, when we first noticed this problem, we spent hours rebuilding indexes on the affected tables. It did not help. If this scenario matches your problem,...

Are you running SQL 2000, service pack 3, on a multi-processor machine? If so, there is a known bug that affects count(*) queries with IS NULL in the WHERE...