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

I use this Function I modified (the Days part) From @Dane answer: https://stackoverflow.com/a/57720/2097023

CREATE FUNCTION dbo.EdadAMD
    (
        @FECHA DATETIME
    )
    RETURNS NVARCHAR(10)
    AS
    BEGIN
        DECLARE
            @tmpdate DATETIME
          , @years   INT
          , @months  INT
          , @days    INT
          , @EdadAMD NVARCHAR(10);

        SELECT @tmpdate = @FECHA;

        SELECT @years = DATEDIFF(yy, @tmpdate, GETDATE()) - CASE
                                          WHEN (MONTH(@FECHA) >    MONTH(GETDATE()))
                                             OR (
                                                MONTH(@FECHA) = MONTH(GETDATE())
                                          AND DAY(@FECHA) > DAY(GETDATE())
                                          ) THEN
                                                1
                                            ELSE
                                                0
                                    END;
    SELECT @tmpdate = DATEADD(yy, @years, @tmpdate);
    SELECT @months = DATEDIFF(m, @tmpdate, GETDATE()) - CASE
                              WHEN DAY(@FECHA) > DAY(GETDATE()) THEN
                                                            1
                                                        ELSE
                                                            0
                                                    END;
    SELECT @tmpdate = DATEADD(m, @months, @tmpdate);

    IF MONTH(@FECHA) = MONTH(GETDATE())
       AND DAY(@FECHA) > DAY(GETDATE())
          SELECT @days = 
            DAY(EOMONTH(GETDATE(), -1)) - (DAY(@FECHA) - DAY(GETDATE()));
    ELSE
        SELECT @days = DATEDIFF(d, @tmpdate, GETDATE());

    SELECT @EdadAMD = CONCAT(@years, 'a', @months, 'm', @days, 'd');

    RETURN @EdadAMD;

END; 
GO

It works pretty well.