grouping by a day

[lance]

Hi

I have a query that groups my order table entries by a month like this:
SELECT month(date_purchased) as month, sum(order_total) as total FROM
`orders` GROUP BY month ORDER BY month

This works fine but now I wanted to group my orders by a day. I can't figure
out how to do this, as there is no day()-function.
The field date_purchased is a datetime field with hours, minutes and seconds
in addition to a date information.

This is what I would like to have but does not work:

SELECT >>DAY(date_purchased)<< as day, sum(order_total) as total FROM
`orders` GROUP BY day ORDER BY day

Any idea what to do?