subquery question

Hi,

I have a table: (date timestamp, id integer, value integer)

What Iam trying to do is to get a result that looks like this:

day sum_odd sum_even
2009-01-01 6565 78867
2009-01-02 876785 87667

basically a need to combine these two queries into one:

SELECT date_trunc('day',date) AS day, sum(value) AS sum_odd
FROM xyz WHERE id % 2 = 1 GROUP BY date_trunc('day',date)
SELECT date_trunc('day',date) AS day, sum(value) AS sum_even
FROM xyz WHERE id % 2 = 0 GROUP BY date_trunc('day',date)

I found various ways to do this via unions or joins, but none of them
seem efficient, what is the best way to do that ?

thank you very much
Sebastian