group by week()

[Phil Glatz]

for is a table with a series of row, one per day
when is a timedate field

select when,week(when) as wk from foo group by wk order by when;

This query does group properly on week numbers, but the date in the 'when'
column is a value from sometime within the week, but not necessarily the
starting day of the week - any way to make this column reflect the first
day of the week?