Show every week of the Year even if there is no data

Question

I have query that pulls data by week and groups it together. But i does not display weeks that doesn\'t have any data. I want show all weeks even if they don\'t have data as nul

Answer 1

You probably need a calendar table. Here is a quick way of generating one, with an untested implementation of your code. I am assuming that the StartDate may contain a time component thus the need to coalesce the dates.

DECLARE @StartYear DATETIME = '20200101'
DECLARE @days      INT      = 366

;WITH
  E1(N) AS (
    SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL 
    SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL 
    SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
  ),                                   -- 1*10^1 or 10 rows
  E2(N) AS (SELECT 1 FROM E1 a, E1 b), -- 1*10^2 or 100 rows
  E4(N) AS (SELECT 1 FROM E2 a, E2 b), -- 1*10^4 or 10,000 rows
  E8(N) AS (SELECT 1 FROM E4 a, E4 b), -- 1*10^8 or 100,000,000 rows
  Tally(N) AS (SELECT TOP (@Days) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E8),
  Calendar AS (
    SELECT  StartOfDay = DATEADD(dd,N-1,@StartYear),
            EndOfDay   = DATEADD(second, -1, DATEADD(dd,N  ,@StartYear))
    FROM Tally)

SELECT  DATEADD (week, datediff(week, 0, COALESCE(x.StartDate, c.StartOfDay) ), -1) as 'WeekOf'
      , DATEADD (week, datediff(week, 0, COALESCE(x.StartDate, c.StartOfDay)), +5) as 'to'
      , DATEPART(wk, COALESCE(x.StartDate, c.StartOfDay)) as 'WeekNumber'
FROM    Calendar c
        INNER JOIN [DESOutage].[dbo].[OPSInterruption] x
                ON x.StartDate > c.StartOfDay AND x.StartDate <= c.EndOfDay
WHERE   c.StartOfDay > '2020-01-01' AND c.StartOfDay <'2020-02-01' 
GROUP BY DATEADD (week, datediff(week, 0, COALESCE(x.StartDate, c.StartOfDay)), -1),
         DATEPART(wk, COALESCE(x.StartDate, c.StartOfDay)),
         DATEADD (week, datediff(week, 0, COALESCE(x.StartDate, c.StartOfDay)), +5)