get total orders for the last 1 month every week - sql-server

Question

I have an "Orders" table containing column CreatedDate (datetime) on when the order took place.
Today is Feb 13, 2014.
How to get total records for the last 4 weeks for every week.
it should return something like this:
PerDate Total
2014-01-26 13 <--- sunday
2014-02-02 24 <--- sunday
2014-02-09 33 <--- sunday
2014-02-13 35 <--- this is today
13 from the first record is the total record from 2014-01-20 00:00:00 AM (monday) to 2014-01-26 12:00:00 PM (sunday)
24 from the 2nd record is the total record from 2014-01-27 00:00:00 AM (monday) to 2014-02-02 12:00:00 PM (sunday)
33 from the 3rd record is the total record from 2014-02-03 00:00:00 AM (monday) to 2014-02-09 12:00:00 PM (sunday)
35 from the 4th record is the total record from 2014-02-10 00:00:00 AM (monday) to 2014-02-13 (today)
so they are in Ascending order.

Answer 1

You should use DATEPART(dw,CreatedDate) function to calculate date of begin and end of the week for each CreatedDate and then just group by this field:
WITH T AS
(
SELECT
cast(floor(cast(CreatedDate as float)) as datetime)
-DATEPART(dw,CreatedDate)+1 as BeginOfweek,
cast(floor(cast(CreatedDate as float)) as datetime)
-DATEPART(dw,CreatedDate)+8 as EndOfWeek
FROM ORDERS
WHERE cast(floor(cast(CreatedDate as float)) as datetime) BETWEEN
DATEADD(WEEK,-4,GETDATE())
AND
GETDATE()
)
SELECT
BeginOfWeek,
MIN(CASE WHEN GETDATE()<EndOfWeek
THEN GETDATE()
ELSE EndOfWeek
END) as EndOfWeek,
Count(*) as OrdersCount
FROM T
Group by BeginOfWeek
SQLFiddle demo