USE [LABORATORY]
GO
/****** Object:  UserDefinedFunction [dbo].[fn_LabComputeAge]    Script Date: 11/21/2017 10:13:48 ******/
SET ANSI_NULLS OFF
GO
SET QUOTED_IDENTIFIER OFF
GO



ALTER FUNCTION [dbo].[fn_LabComputeAge] (@BirthDate as datetime, @DateToday as datetime)
RETURNS varchar(3) AS 
BEGIN
	declare @Age as varchar(3)
	declare @d1 as int
	declare @d2 as int
	declare @m1 as int
	declare @m2 as int
	declare @y1 as int
	declare @y2 as int

	declare @dAge as int
	declare @mAge as int
	declare @yAge as int
	

	if @birthdate <= '01/01/1900' or @birthdate > getdate()
		set @age = ''
	else	
		begin
			set @y1 = year(@BirthDate)
			set @m1 = month(@BirthDate)
			set @d1 = day(@BirthDate)
		
			set @y2 = year(getdate())
			set @m2 = month(getdate())
			set @d2 = day(getdate())
		
			if @d2 < @d1
			begin
		 	    set @d2 = @d2 + 30
		  	    set @m2 = @m2 - 1
			end
		
			set @dAge = datediff(day, @BirthDate, getdate())
		
			if @m2 < @m1
			    begin
		  		set @m2 = @m2 + 12
		  		set @y2 = @y2 - 1
			    end
		
			set @mAge = @m2 - @m1
		
			set @yAge = @y2 - @y1
		
			if @yAge = 0
		  	    if @mAge = 0
				Begin
				   If @dAge = 0 
					Set @Age = cast(@dAge as varchar(3))
				   else 
					 set @Age = cast(@dAge as varchar(3)) + 'D'  
				End
		  	    else
					 set @Age = cast(@mAge as varchar(3)) + 'M'
			else
		   	    set @Age = cast(@yAge as varchar(3))  	
		end
Return @Age

END