T-SQL: calculate age then add character to result

Question

Been stuck on this one for a while now. Let\'s say I have a Client table like the one here:

Name   BirthDayNum   BirthMonthNum   BirthYearNum
--         


        

Answer 1

Tired of twisting myself into knots with date calculations, I created a Table-Valued-Function to calculate elapsed time in Years, Months, Days, Hours, Minutes, and Seconds.

Example

Declare @YourTable table (Name varchar(50),BirthDayNum int, BirthMonthNum int, BirthYearNum int)
Insert Into @YourTable values
('John', 23, 12, 1965),
('Jane',  4, 9,  1975),
('Joe',   6, 3,  1953)

Select A.Name
      ,B.*
      ,Age =  concat(C.Years,'y ',C.Months,'m')
 From @YourTable A
 Cross Apply (Select DOB = DateFromParts(A.BirthYearNum,A.BirthMonthNum,A.BirthDayNum)) B
 Cross Apply [dbo].[udf-Date-Elapsed](B.DOB,GetDate()) C

Returns

Name    DOB         Age
John    1965-12-23  51y 3m
Jane    1975-09-04  41y 6m
Joe     1953-03-06  64y 0m

The UDF - May look like overkill, but it is very performant

CREATE FUNCTION [dbo].[udf-Date-Elapsed] (@D1 DateTime,@D2 DateTime)
Returns Table
Return (
    with cteBN(N)   as (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
         cteRN(R)   as (Select Row_Number() Over (Order By (Select NULL))-1 From cteBN a,cteBN b,cteBN c),
         cteYY(N,D) as (Select Max(R),Max(DateAdd(YY,R,@D1))From cteRN R Where DateAdd(YY,R,@D1)<=@D2),
         cteMM(N,D) as (Select Max(R),Max(DateAdd(MM,R,D))  From (Select Top 12 R From cteRN Order By 1) R, cteYY P Where DateAdd(MM,R,D)<=@D2),
         cteDD(N,D) as (Select Max(R),Max(DateAdd(DD,R,D))  From (Select Top 31 R From cteRN Order By 1) R, cteMM P Where DateAdd(DD,R,D)<=@D2),
         cteHH(N,D) as (Select Max(R),Max(DateAdd(HH,R,D))  From (Select Top 24 R From cteRN Order By 1) R, cteDD P Where DateAdd(HH,R,D)<=@D2),
         cteMI(N,D) as (Select Max(R),Max(DateAdd(MI,R,D))  From (Select Top 60 R From cteRN Order By 1) R, cteHH P Where DateAdd(MI,R,D)<=@D2),
         cteSS(N,D) as (Select Max(R),Max(DateAdd(SS,R,D))  From (Select Top 60 R From cteRN Order By 1) R, cteMI P Where DateAdd(SS,R,D)<=@D2)

    Select [Years]   = cteYY.N
          ,[Months]  = cteMM.N
          ,[Days]    = cteDD.N
          ,[Hours]   = cteHH.N
          ,[Minutes] = cteMI.N
          ,[Seconds] = cteSS.N
     From  cteYY,cteMM,cteDD,cteHH,cteMI,cteSS
)
--Max 1000 years
--Select * from [dbo].[udf-Date-Elapsed] ('1991-09-12 21:00:00.000',GetDate())

Just to Illustrate

The TVF without any secondary string manipulation would return

Select A.Name
      ,B.*
 From @YourTable A
 Cross Apply [dbo].[udf-Date-Elapsed](DateFromParts(A.BirthYearNum,A.BirthMonthNum,A.BirthDayNum),GetDate()) B

EDIT - READ ONLY VERSION

Select A.Name
      ,B.*
      ,Age =  concat(DateDiff(MONTH,B.DOB,GetDate())/12,'y ',DateDiff(MONTH,B.DOB,GetDate()) % 12,'m')
 From @YourTable A
 Cross Apply (Select DOB = DateFromParts(A.BirthYearNum,A.BirthMonthNum,A.BirthDayNum)) B

Answer 2

Yes it is easier to save as DOB.. But one simple method

select concat( floor(datediff(year, datefromparts(birthyearnum,birthmonthnum,birthdaynum), getdate()))-1, 'y ', datediff(month, datefromparts(birthyearnum,birthmonthnum,birthdaynum), getdate())%12, 'm')
    from #yourDates

How age for 1965 is 41y?

Input table:

create table #yourdates(Name varchar(10), BirthdayNum int, BirthMonthNum int, BirthYearNum int)

insert into #yourdates
(Name, BirthdayNum, BirthMonthNum, BirthYearNum) values
 ('John',      23        ,     12     ,        1965  )
,('Jane',       4        ,      9     ,        1975  )
,('Joe ',       6        ,      3     ,        1953  )

Answer 3

If you are on 2008 or lesser and can't use datefromparts...

declare @table table ([Name] varchar(4), BirthDayNum int, BirthMonthNum int, BirthYearNum int)
insert into @table
values
('John',23,12,1965),
('Jane',4,9,1975),
('Day',30,3,1990)

;with cte as(
    select
        [Name],
        cast(BirthYearNum as varchar(4)) + '/' + cast(BirthMonthNum as varchar(2)) + '/' + cast(BirthDayNum as varchar(2)) as DOB
    from 
        @table)

select 
     [Name]
     ,DOB
     ,datediff(year,DOB,GETDATE()) as Years
     ,datediff(month,DOB,GETDATE()) %12 as Months
     ,rtrim(cast(datediff(year,DOB,GETDATE()) as char(2))) + 'y ' + rtrim(cast(datediff(month,DOB,GETDATE()) %12 as char(2))) + 'm' as  Age 
from cte