Dynamic update

Is it possible to update a column with another column's value, say

UPDATE member SET votes = `SELECT count(votes) FROM ballot WHERE id = 1`;

with or without aggregates?

Tried everything I can think of, searched the docs, reading the finished parts
of Bruce's book...

If not, are there truly dynamic SQL-only (i.e. without resorting to external
functions) ways to achieve this? Am I being obtuse and missing something
obvious?


Simon.

-- 
 "Linux - open doors, not windows."
   
   Simon Drabble                      It's like karma for your brain.
   simon@eskimo.com