GROUP BY WEEK with SQL - sql

Question

I have the following:
http://sqlfiddle.com/#!6/226ae/1
I'm trying to now add one row for each week of the year, and filter the contacts accordingly. CONTACTS has a datetime column. The new table will look like:
Status 1 Status 2 Status 3
Week 1 3 4 2
Week 2 1 5 3
Week 3 2 2 4
I think that DATEADD needs to be used, however I'm at a loss in terms of how to begin changing my query.
I do know that MySQL has a GROUP BY WEEK command, but I don't think that SQL has an equivalent. What's the best way to accomplish this?

Answer 1

You can use DATEPART(), this groups by both the week and the year in the event you have data spanning multiple years:
SELECT
'Week ' + cast(datepart(wk, created) as varchar(2)) Week,
SUM(case WHEN status = 1 then 1 else 0 end) Status1,
SUM(case WHEN status = 2 then 1 else 0 end) Status2,
SUM(case WHEN status = 3 then 1 else 0 end) Status3,
SUM(case WHEN status = 4 then 1 else 0 end) Status4,
SUM(case WHEN status = 5 then 1 else 0 end) Status5
FROM contacts
group by datepart(wk, created), year(created)
See SQL Fiddle with Demo
Adding the year to the final result:
SELECT
'Week ' + cast(datepart(wk, created) as varchar(2)) Week,
year(created) year,
SUM(case WHEN status = 1 then 1 else 0 end) Status1,
SUM(case WHEN status = 2 then 1 else 0 end) Status2,
SUM(case WHEN status = 3 then 1 else 0 end) Status3,
SUM(case WHEN status = 4 then 1 else 0 end) Status4,
SUM(case WHEN status = 5 then 1 else 0 end) Status5
FROM contacts
group by datepart(wk, created), year(created)
See SQL Fiddle with demo

Answer 2

You can use the datepart function to extract the week from a date.
The query becomes:
SELECT datepart(week, created) as week,
SUM(case WHEN status = 1 then 1 else 0 end) Status1,
SUM(case WHEN status = 2 then 1 else 0 end) Status2,
SUM(case WHEN status = 3 then 1 else 0 end) Status3,
SUM(case WHEN status = 4 then 1 else 0 end) Status4,
SUM(case WHEN status = 5 then 1 else 0 end) Status5
FROM contacts
group by datepart(week, created)
SqlFiddle: http://sqlfiddle.com/#!6/226ae/6tsq

Answer 3

You might try using the group by clause in your query:
SELECT
DATE_FORMAT( created, '%u' ) week_number,
SUM(case WHEN status = 1 then 1 else 0 end) Status1,
SUM(case WHEN status = 2 then 1 else 0 end) Status2,
SUM(case WHEN status = 3 then 1 else 0 end) Status3,
SUM(case WHEN status = 4 then 1 else 0 end) Status4,
SUM(case WHEN status = 5 then 1 else 0 end) Status5
FROM contacts
GROUP BY DATE_FORMAT( created, '%u' )
I'm assuming you are talking about mysql.
The DATE_FORMAT function is documented here:
http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_date-format