CREATE OR ALTER FUNCTION AGE(DFROM TIMESTAMP, DTO TIMESTAMP, CODED BOOLEAN = FALSE)
RETURNS VARCHAR(30)
AS
DECLARE y varchar(3);
DECLARE m varchar(2);
DECLARE d varchar(2);
BEGIN
	y = CASE 
			WHEN datediff(year, :DFROM, :DTO) <> datediff(day, :DFROM, :DTO)/365
				THEN datediff(year, :DFROM, :DTO)-1
			ELSE datediff(year, :DFROM, :DTO)
		END;
	m = CASE 
			WHEN datediff(year, :DFROM, :DTO) <> datediff(day, :DFROM, :DTO)/365
				AND datediff(day, dateadd(month, datediff(month, :DFROM, :DTO), :DFROM), :DTO)<0
				THEN datediff(month, dateadd(year, datediff(year, :DFROM, :DTO)-1, :DFROM), :DTO)-1
			WHEN datediff(year, :DFROM, :DTO) <> datediff(day, :DFROM, :DTO)/365
				AND datediff(day, dateadd(month, datediff(month, :DFROM, :DTO), :DFROM), :DTO)>=0
				THEN datediff(month, dateadd(year, datediff(year, :DFROM, :DTO)-1, :DFROM), :DTO)
			WHEN datediff(year, :DFROM, :DTO) = datediff(day, :DFROM, :DTO)/365
				AND datediff(day, dateadd(month, datediff(month, :DFROM, :DTO), :DFROM), :DTO)<0
				THEN datediff(month, dateadd(year, datediff(year, :DFROM, :DTO), :DFROM), :DTO)-1
			ELSE datediff(month, dateadd(year, datediff(year, :DFROM, :DTO), :DFROM), :DTO)
		END;
	d = CASE 
			WHEN datediff(day, dateadd(month, datediff(month, :DFROM, :DTO), :DFROM), :DTO)<0
				THEN datediff(day, dateadd(month, datediff(month, :DFROM, :DTO)-1, :DFROM), :DTO)
			ELSE datediff(day, dateadd(month, datediff(month, :DFROM, :DTO), :DFROM), :DTO)
		END;
	RETURN 
		CASE 
			WHEN :CODED THEN lpad(Y,3,'0')||'-'||lpad(m,2,'0')||'-'||lpad(d,2,'0')
			ELSE Y||'y '||m||'m '||d||'d' 
		END;
END;