How to calculate age in T-SQL with years, months, and days

Question

What would be the best way to calculate someone\'s age in years, months, and days in T-SQL (SQL Server 2000)?

The datediff function doesn\'t handle year

Answer 1

create  procedure getDatedifference

(
    @startdate datetime,
    @enddate datetime
)
as
begin
    declare @monthToShow int
    declare @dayToShow int

    --set @startdate='01/21/1934'
    --set @enddate=getdate()

    if (DAY(@startdate) > DAY(@enddate))
        begin
            set @dayToShow=0

            if (month(@startdate) > month(@enddate))
                begin
                    set @monthToShow=  (12-month(@startdate)+ month(@enddate)-1)
                end
            else if (month(@startdate) < month(@enddate))
                begin
                    set @monthToShow=  ((month(@enddate)-month(@startdate))-1)
                end
            else
               begin
                   set @monthToShow=  11
               end
            -- set @monthToShow= convert(int, DATEDIFF(mm,0,DATEADD(dd,DATEDIFF(dd,0,@enddate)- DATEDIFF(dd,0,@startdate),0)))-((convert(int,FLOOR(DATEDIFF(day, @startdate, @enddate) / 365.25))*12))-1
                         if(@monthToShow<0)
                         begin
                            set @monthToShow=0
                         end

                      declare @amonthbefore integer
                      set @amonthbefore=Month(@enddate)-1
                          if(@amonthbefore=0)
                             begin
                                set @amonthbefore=12
                              end


                      if (@amonthbefore  in(1,3,5,7,8,10,12))
                          begin
                            set @dayToShow=31-DAY(@startdate)+DAY(@enddate)
                          end
                      if (@amonthbefore=2)
                         begin
                           IF (YEAR( @enddate ) % 4 = 0 AND YEAR( @enddate ) % 100 != 0) OR  YEAR( @enddate ) % 400 = 0
                                 begin
                                    set @dayToShow=29-DAY(@startdate)+DAY(@enddate)
                                  end
                           else
                               begin
                                   set @dayToShow=28-DAY(@startdate)+DAY(@enddate)
                           end
                      end
                      if (@amonthbefore in (4,6,9,11))
                        begin
                           set @dayToShow=30-DAY(@startdate)+DAY(@enddate)
                        end
                 end
    else
        begin
          --set @monthToShow=convert(int, DATEDIFF(mm,0,DATEADD(dd,DATEDIFF(dd,0,@enddate)- DATEDIFF(dd,0,@startdate),0)))-((convert(int,FLOOR(DATEDIFF(day, @startdate, @enddate) / 365.25))*12))
          if (month(@enddate)< month(@startdate))
              begin
                 set @monthToShow=12+(month(@enddate)-month(@startdate))
              end
          else
              begin
                set @monthToShow= (month(@enddate)-month(@startdate))
              end
          set @dayToShow=DAY(@enddate)-DAY(@startdate)
        end

    SELECT
        FLOOR(DATEDIFF(day, @startdate, @enddate) / 365.25) as [yearToShow],
          @monthToShow as  monthToShow ,@dayToShow as dayToShow ,
        convert(varchar,FLOOR(DATEDIFF(day, @startdate, @enddate) / 365.25)) +' Year ' + convert(varchar,@monthToShow) +' months '+convert(varchar,@dayToShow)+' days ' as age

    return
end