从年份和周数的组合中提取一周中的 7 天作为日期？

Question

I have a table (SQL Server 2017) where the data is stored at the level of the year number and week number.

    +---------+-------------+---------+----------+-----+
    | year_id | week_number | good_id | store_id | qty |
    +---------+-------------+---------+----------+-----+
    | 2019    | 42          | 113466  | 41       | 7   |
    +---------+-------------+---------+----------+-----+

I need to get a similar table, but at the day level, where the quantity ( qty ) will be divided into 7 parts evenly for each day.

+---------+-------------+---------+----------+-----+------------+
| year_id | week_number | good_id | store_id | qty | date_id    |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-14 |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-15 |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-16 |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-17 |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-18 |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-19 |
+---------+-------------+---------+----------+-----+------------+
| 2019    | 42          | 113466  | 41       | 1   | 2019-10-20 |
+---------+-------------+---------+----------+-----+------------+

I found a way to get a date from the year and week number , but how do I get 7 rows from one at once?

Answer 1

You can create a calendar table as shown here and join the original table as shown below to get the desired output.

Select 
      CalendarDate
      , year_id
      , week_number
      , good_id
      , store_id
      , 1 as qty
from dbo.RunningNumbers
inner join ToBeGenerated on CalendarYear = year_id and week_number = CalendarWeek

Here is the live db<>fiddle demo.

Answer 2

There you go. You need to join a table with all the dates and then divide the qty by the value you want:

use tempdb

CREATE TABLE tbl1
(
   year_id INT, week_number INT, good_id INT, store_id INT, qty INT
)

INSERT INTO tbl1
VALUES (2019, 42, 113466, 41, 7)
GO
WITH sample AS(
   SELECT CAST('2019-10-01' AS DATE) as DT
   UNION ALL
   SELECT DATEADD(dd,1,dt)
    FROM sample
   WHERE DATEADD(dd,1,dt) < CAST('2019-12-31' AS DATE))

SELECT dt, YEAR(dt) AS [Year], DATEPART(WEEK,dt) AS Week
INTO wks
FROM sample

SELECT t.year_id, t.week_number, t.good_id, t.store_id, qty/7 AS [Qty], dt AS [Date]
  FROM tbl1 t
 INNER JOIN wks S on s.Week = t.week_number