CODEWITHSUNDEEP
sqlsql-servert-sql
Jason C
Jason C

Reputation: 37

I need to use Cross Apply to get a table with a value for every date

I have a query that returns these results:

ID     | From        | To         |  Value
------ | ---------   | ---------- | -------
8      | 1/1/2018    | 2/28/2018  |  .03
8      | 3/1/2018    | 4/30/2018  |  .04
9      | 1/1/2018    | 1/31/2018  |  .05

What I need is this:

ID     | Date        | Value        
------ | ---------   | ---------- 
8      | 1/1/2018    | .03  
8      | 2/1/2018    | .03  
8      | 3/1/2018    | .04
8      | 4/1/2018    | .04
9      | 1/1/2018    | .05

I have researched and it seems like Cross Apply needs to be used here along with date table, but just not sure how to use this operator.

Thanks in advance!

Upvotes: 1

Views: 3378

Answers (2)

Rodrick Chapman
Rodrick Chapman

Reputation: 5543

Since John Cappelletti mentioned calendar tables, and since I'm always looking for an excuse to extol the virtue of using them, I'll just point out that if you have a Calendar table then the solution is simply:

select T.id, S.date, T.value from YourTable T
cross apply
(
    select date from Calendar where date between T.[from] and T.[to] and day_of_month = 1
) S order by T.id, S.date asc

Which yields:

id      date       value  
------ ----------  ------- 
8      2018-01-01  0.03    
8      2018-02-01  0.03    
8      2018-03-01  0.04    
8      2018-04-01  0.04    
9      2018-01-01  0.05

And here's all it takes to create a Calendar table:

create table Calendar
(
    id int primary key identity,
    date datetime,
    day_of_week as datepart(dw, date),
    day_of_month as datepart(d, date),
    month as datepart(m, date),
    year as datepart(yy, date),
    day_name as datename(dw, date)
    --etc...
)

--and populate

declare @day datetime
set @day = '1/1/2000'

while @day <= '12/31/2100'
begin

    insert Calendar select @day
    set @day = dateadd(day, 1, @day)

end

Upvotes: 3

John Cappelletti
John Cappelletti

Reputation: 81970

One approach is using an ad-hoc tally table within the CROSS APPLY. A numbers or calendar table would do the trick as well.

Example

Select A.ID
      ,B.Date
      ,A.Value
 From  YourTable A
 Cross Apply (
              Select Top (DateDiff(MONTH,A.[From],A.[To])+1) 
                     Date=DateAdd(MONTH,-1+Row_Number() Over (Order By (Select Null)),A.[From]) 
               From  master..spt_values n1
             ) B

Returns

enter image description here

EDIT - If Open to a UDF

I'll often use a UDF to create dynamic date/time ranges. It is faster than a recursive cte and it is parameter driven. You supply the date/time range, datepart, and increment.

Example of UDF 

Select A.ID
      ,Date = cast(B.RetVal as date)
      ,A.Value
 From YourTable A
 Cross Apply [dbo].[udf-Range-Date](A.[From],A.[To],'MM',1) B

The UDF if Interested

CREATE FUNCTION [dbo].[udf-Range-Date] (@R1 datetime,@R2 datetime,@Part varchar(10),@Incr int)
Returns Table
Return (
    with cte0(M)   As (Select 1+Case @Part When 'YY' then DateDiff(YY,@R1,@R2)/@Incr When 'QQ' then DateDiff(QQ,@R1,@R2)/@Incr When 'MM' then DateDiff(MM,@R1,@R2)/@Incr When 'WK' then DateDiff(WK,@R1,@R2)/@Incr When 'DD' then DateDiff(DD,@R1,@R2)/@Incr When 'HH' then DateDiff(HH,@R1,@R2)/@Incr When 'MI' then DateDiff(MI,@R1,@R2)/@Incr When 'SS' then DateDiff(SS,@R1,@R2)/@Incr End),
         cte1(N)   As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
         cte2(N)   As (Select Top (Select M from cte0) Row_Number() over (Order By (Select NULL)) From cte1 a, cte1 b, cte1 c, cte1 d, cte1 e, cte1 f, cte1 g, cte1 h ),
         cte3(N,D) As (Select 0,@R1 Union All Select N,Case @Part When 'YY' then DateAdd(YY, N*@Incr, @R1) When 'QQ' then DateAdd(QQ, N*@Incr, @R1) When 'MM' then DateAdd(MM, N*@Incr, @R1) When 'WK' then DateAdd(WK, N*@Incr, @R1) When 'DD' then DateAdd(DD, N*@Incr, @R1) When 'HH' then DateAdd(HH, N*@Incr, @R1) When 'MI' then DateAdd(MI, N*@Incr, @R1) When 'SS' then DateAdd(SS, N*@Incr, @R1) End From cte2 )

    Select RetSeq = N+1
          ,RetVal = D 
     From  cte3,cte0 
     Where D<=@R2
)
/*
Max 100 million observations -- Date Parts YY QQ MM WK DD HH MI SS
Syntax:
Select * from [dbo].[udf-Range-Date]('2016-10-01','2020-10-01','YY',1) 
Select * from [dbo].[udf-Range-Date]('2016-01-01','2017-01-01','MM',1) 
*/

Upvotes: 2

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