Question

I got this example from one StackOverflow question that was asked but I couldn’t get it work according to my need.

WITH DateTable
AS
(
    SELECT CAST('20110101' as Date) AS [DATE]
    UNION ALL
    SELECT DATEADD(dd, 1, [DATE]) FROM DateTable 
    WHERE DATEADD(dd, 1, [DATE]) < cast('20110131' as Date)
)
SELECT dt.[DATE] FROM [DateTable] dt

Input-

ID |   FromDate  | ToDate
=============================
1  |  2011-11-10 | 2011-11-12
2  |  2011-12-12 | 2011-12-14

Output –

SN |   Dates     | 
==================
1  |  2011-11-10 | 
2  |  2011-11-11 | 
3  |  2011-11-12 | 
4  |  2011-12-12 | 
5  |  2011-12-13 | 
6  |  2011-12-14 |

See this code works fine for static dates. But in my case I have a table containing three columns Id, FromDate, ToDate. Now I want to convert each range in the every row to individual dates.

I cannot get the above example to work in case if the range comes from the table and obviously this query has to run for every row in the range table, which is another confusing challenge.

Please help.

Answer 1

With a little help of a numbers table.

declare @T table
(
  ID int identity primary key,
  FromDate date,
  ToDate date
)

insert into @T values
('2011-11-10', '2011-11-12'),
('2011-12-12', '2011-12-14')

select row_number() over(order by D.Dates) as SN,
       D.Dates
from @T as T
  inner join master..spt_values as N
    on N.number between 0 and datediff(day, T.FromDate, T.ToDate)
    cross apply (select dateadd(day, N.number, T.FromDate)) as D(Dates)
where N.type ='P'

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