sqlsql-serverdatabasesql-server-2005t-sql

Generate a resultset of incrementing dates in T-SQL

Consider the need to create a resultset of dates. We've got start and end dates, and we'd like to generate a list of dates in between.

DECLARE  @Start datetime
         ,@End  datetime
DECLARE @AllDates table
        (@Date datetime)

SELECT @Start = 'Mar 1 2009', @End = 'Aug 1 2009'

--need to fill @AllDates. Trying to avoid looping. 
-- Surely if a better solution exists.

Consider the current implementation with a WHILE loop:

DECLARE @dCounter datetime
SELECT @dCounter = @Start
WHILE @dCounter <= @End
BEGIN
 INSERT INTO @AllDates VALUES (@dCounter)
 SELECT @dCounter=@dCounter+1 
END

How would you create a set of dates that are within a user-defined range using T-SQL?

Assume SQL Server 2005 or later. If your answer is using SQL Server 2008 features, please mark as such.

Solution

  • If your dates are no more than 2047 days apart:

    declare @dt datetime, @dtEnd datetime
set @dt = getdate()
set @dtEnd = dateadd(day, 100, @dt)

select dateadd(day, number, @dt)
from 
    (select number from master.dbo.spt_values
     where [type] = 'P'
    ) n
where dateadd(day, number, @dt) < @dtEnd

    I updated my answer after several requests to do so. Why?

    The original answer contained the subquery

     select distinct number from master.dbo.spt_values
     where name is null

    which delivers the same result, as I tested them on SQL Server 2008, 2012, and 2016.

    However, as I tried to analyze the code that MSSQL internally when querying from spt_values, I found that the SELECT statements always contain the clause WHERE [type]='[magic code]'.

    Therefore I decided that although the query returns the correct result, it delivers the correct result for wrong reasons:

    There may be a future version of SQL Server which defines a different [type] value which also has NULL as values for [name], outside the range of 0-2047, or even non-contiguous, in which case the result would be simply wrong.