SQL Server 2017

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create table orders(id int identity, dt_created date);

insert into  orders (dt_created) values
('20180101'),('20180108'),('20180109'),('20180110'),('20180112'),
('20180113'),('20180114'),('20180115'),('20180116'),('20180117'),
('20180118'),('20180120'),('20180121'),('20180122'),('20180123');
15 rows affected

SELECT
    DATEPART(WK, dt_created) week,
    COUNT(*) CT
FROM
    orders
GROUP BY
    DATEPART(WK, dt_created)


week
CT


1
1

2
5

3
6

4
3


WITH WK AS
(
SELECT
    DATEPART(WK, dt_created) week,
    COUNT(*) CT
FROM
    orders
GROUP BY
    DATEPART(WK, dt_created)
)
SELECT
    week,
    SUM(CT) OVER (ORDER BY week) total
FROM
    WK;


week
total


1
1

2
6

3
12

4
15