## Best Way to Calculate Age

 Author Message Jimi Meyer SSCommitted Group: General Forum Members Points: 1522 Visits: 757 Only the second query is getting the right answer. #1 and #3 are getting +1 to the my current age. Tommy Bollhofer Ten Centuries Group: General Forum Members Points: 1166 Visits: 3359 The third solution is clearly incorrect - given a datetime value of 01/26/1978. i.e.`declare @DateOfBirth datetimeset @DateOfBirth = '1978-01-26 00:00:00.000'select @DateOfBirthselect DATEDIFF(yy, @DateOfBirth, GETDATE()) select FLOOR(CONVERT(decimal(9, 2), DATEDIFF(d, @DateOfBirth, GETDATE())) / 365.0) select DATEDIFF(yy, @DateOfBirth, GETDATE()) - CASE WHEN DATEPART(m, @DateOfBirth) >= DATEPART(m, GETDATE()) AND DATEPART(d, @DateOfBirth) >= DATEPART(d, GETDATE()) THEN 0 ELSE 1 END `Returns:30 - Correct30 - Correct29 - Incorrect TommyFollow @sqlscribe Peter Brinkhaus SSCommitted Group: General Forum Members Points: 1676 Visits: 7064 I intuitively choose 2 because 1 and 3 are definitely wrong. 1 doesn't take care of month and day of birth at all and 3 does it in the wrong way. But the are all wrong. It can be easily verified with the script below. Play around with some values at the beginning and end of the month in both dates. I added a fourth solution which I think is correct.`declare @DateOfBirth datetimedeclare @Today datetimeselect @DateOfBirth = '2004/03/01'select @Today = '2008/02/29'select DATEDIFF(yy, @DateOfBirth, @today) select FLOOR(CONVERT(decimal(9, 2), DATEDIFF(d, @DateOfBirth, @Today)) / 365.0) select DATEDIFF(yy, @DateOfBirth, @today) - CASE WHEN DATEPART(m, @DateOfBirth) >= DATEPART(m, @Today) AND DATEPART(d, @DateOfBirth) >= DATEPART(d, @Today) THEN 0 ELSE 1 END select DATEDIFF(yy, @DateOfBirth, @today) - CASE WHEN DATEPART(m, @Today) > DATEPART(m, @DateOfBirth) OR (DATEPART(m, @Today) = DATEPART(m, @DateOfBirth) AND DATEPART(d, @Today) >= DATEPART(d, @DateOfBirth)) THEN 0 ELSE 1 END ` StarNamer Ten Centuries Group: General Forum Members Points: 1294 Visits: 1992 Of course, I suppose the real point of the question was to draw attention to the fact that (1) was wrong and (2) was inaccurate. But it would have been helpful to have a correct solution in the mix. Derek Steven Cameron SSCrazy Group: General Forum Members Points: 2057 Visits: 215 I originally thought the 1 and 0 were switched but actually, the two comparisons should be >= Patrick Cahill Hall of Fame Group: General Forum Members Points: 3708 Visits: 986 I also ran all three queries with my birthdate, and the first and third returned the wrong answer. However, the second one was correct. andre.deslauriers SSC Journeyman Group: General Forum Members Points: 96 Visits: 44 That one works flawlessly.DECLARE @DateOfBirth VARCHAR(10)SET @DateOfBirth = '1960-03-07'print YEAR(GETDATE()) - YEAR(@DateOfBirth) - CASE WHEN MONTH(GETDATE())*31 + DAY(GETDATE()) >= MONTH(@DateOfBirth)*31 + DAY(@DateOfBirth) THEN 0 ELSE 1 END Q -631159 SSC Veteran Group: General Forum Members Points: 241 Visits: 165 The formula is incorrect. If your birthday has occurred in the calendar year, the formula below returns 1 year less than it should. I know many people that would be happy if the formula was correct, but I am afraid they really are the age that DATEDIFF(yy, DateOfBirth, GETDATE()) gives.DATEDIFF(yy, DateOfBirth, GETDATE()) - CASE WHEN DATEPART(m, DateOfBirth) >= DATEPART(m, GETDATE()) AND DATEPART(d, DateOfBirth) >= DATEPART(d, GETDATE()) THEN 0 ELSE 1 END QPlease take a number. Now serving emergency 1,203,894 Simon Facer SSCommitted Group: General Forum Members Points: 1587 Visits: 724 Another point - the question specifies TINYINT, none of the queries return TINYINT. (1) is INT, (2) is DECIMAL, (3) is INT. Not only are the queries inaccurate, but none of them fit the criteria ... jgaroutte SSC Veteran Group: General Forum Members Points: 228 Visits: 61 sorry the 3rd answer is not 100% correct as writtenDECLARE @DateOfBirth DATETIMESET @DateOfBirth='08/xx/1975' --commented out the day just becauseSELECT DATEDIFF(yy, @DateOfBirth, GETDATE()) AS [first], FLOOR(CONVERT(decimal(9, 2), DATEDIFF(d, @DateOfBirth, GETDATE())) / 365.0) AS [second],DATEDIFF(yy, @DateOfBirth, GETDATE()) - CASE WHEN DATEPART(m, @DateOfBirth) >= DATEPART(m, GETDATE()) AND DATEPART(d, @DateOfBirth) >= DATEPART(d, GETDATE()) THEN 0 ELSE 1 END AS [third]the result when it runsfirst   second   third33   32   33Don't age me before my time, only the second one was correct.