I just finished writing a query that groups data based on the week number.
SELECT EXTRACT(week FROM col_a) AS week_number, sum(col_b) AS col_b_total FROM foo WHERE foobar GROUP BY EXTRACT(week FROM col_a) ORDER BY EXTRACT(week FROM col_a);
I would like to generate the starting date or ending date based on this number. IOW instead of telling the user "week number" which they won't understand I would like to provide either Friday's date for "week ending" or Monday's date for "week beginning".
SELECT <something> AS week_ending, sum(col_b) AS col_b_total FROM foo WHERE foobar GROUP BY EXTRACT(week FROM col_a) ORDER BY EXTRACT(week FROM col_a);
Try this. It puts Saturday as the Friday before it and Sunday as the Firday after so if you want Saturday or Sunday to be on different weeks you will need to do a little tweaking but this should get you going.
SELECT date_trunc('day', col_a + (interval '1 day' * (5 - extract(dow from col_a)))) AS week_ending, sum(col_b) AS col_b_total FROM foo GROUP BY date_trunc('day', col_a + (interval '1 day' * (5 - extract(dow from col_a))))
