Question

I just want a quick way (and preferably not using a while loop)of createing a table of every date between date @x and date @y so I can left outer join to some stats tables, some of which will have no records for certain days in between, allowing me to mark missing days with a 0

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Solution

Strictly speaking this doesn't exactly answer your question, but its pretty neat.

Assuming you can live with specifying the number of days after the start date, then using a Common Table Expression gives you:

WITH numbers ( n ) AS (
        SELECT 1 UNION ALL
        SELECT 1 + n FROM numbers WHERE n < 500 )
    SELECT DATEADD(day,n-1,'2008/11/01') FROM numbers
    OPTION ( MAXRECURSION 500 )

OTHER TIPS

I believe you're looking for this blog post.

I would create a Calendar table that just contained every date from a suitable start date until a suitable end date. This wouldn't take up much space in your database and would make these types of query child's play.

select  ...
from    Calendar
        left outer join
        ...
where   Calendar.Date >= @x
and     Calendar.Date <= @y

I think that you might as well just do it in a while loop. I know it's ugly, but it's easy and it works.

I was actually doing something similar a little while back, but I couldn't come up with a way that didn't use a loop.

The best I got was a temp table, and then selecting the dates I wanted to join on into that.

The blog bduke linked to is cute, although I think the temp table solution is perhaps a cleaner solution.

I've found another table that stores every date (it's visitors to the website), so how about this...

Declare @FromDate datetime,  
        @ToDate datetime  
Declare @tmpDates table   
            (StatsDate datetime)
Set @FromDate = DateAdd(day,-30,GetDate())
Set @ToDate = GetDate()

Insert Into  @tmpDates (StatsDate)
Select 
    distinct CAST(FLOOR(CAST(visitDate AS DECIMAL(12, 5))) AS DATETIME)
FROM tbl_visitorstats 
Where visitDate between @FromDate And @ToDate 
Order By CAST(FLOOR(CAST(visitDate AS DECIMAL(12, 5))) AS DATETIME) 


Select * FROM @tmpDates

It does rely on the other table having an entry for every date I want, but it's 98% likely there'll be data for every day.

A slight twist on the answer given as https://stackoverflow.com/a/95728/395440. Allows days to be specified and also calculates range up to the current date.

DECLARE @startDate datetime
SET @startDate = '2015/5/29';

WITH number ( n ) AS (
        SELECT 1 UNION ALL
        SELECT 1 + n FROM dates WHERE n < DATEDIFF(Day, @startDate, GETDATE()) )
    SELECT DATEADD(day,n-1,@startDate) FROM number where
    datename(dw, DATEADD(day,n-1,@startDate)) in ('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday')
    OPTION ( MAXRECURSION 500 )

Just write the loop. Someone has to write a loop for this, be it you - or SQL Server.

DECLARE @Dates TABLE
(
  TheDate datetime PRIMARY KEY
)
DECLARE @StartDate datetime, @EndDate datetime
SELECT @StartDate = '2000-01-01', @EndDate = '2010-01-01'


DECLARE @LoopVar int, @LoopEnd int    
SELECT @LoopEnd = DateDiff(dd, @StartDate, @EndDate), @LoopVar = 0


WHILE @LoopVar <= @LoopEnd
BEGIN
  INSERT INTO @Dates (TheDate)
  SELECT DateAdd(dd,@LoopVar,@StartDate)

  SET @LoopVar = @LoopVar + 1
END


SELECT *
FROM @Dates

Just: WHERE col > start-date AND col < end-date

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