Yep, you read the title correctly. This problem presented itself when I needed a quick and dirty way to update an auto_increment [a_i] field in a database. I wanted to move the a_i field up by n, where a_i > x. The query looked like this:

UPDATE table_name SET id = (id + n) WHERE id > x ORDER BY id DESC

To see why one must do it this way, try to do the query without the SORT BY.

Nick