## Best Way to Calculate Age

 Author Message Jimi Meyer SSCommitted Group: General Forum Members Points: 1615 Visits: 831 Only the second query is getting the right answer. #1 and #3 are getting +1 to the my current age. Tommy Bollhofer SSCrazy Eights Group: General Forum Members Points: 9258 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 SSCertifiable Group: General Forum Members Points: 6060 Visits: 7426 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 SSCertifiable Group: General Forum Members Points: 5020 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: 2405 Visits: 215 I originally thought the 1 and 0 were switched but actually, the two comparisons should be >= Patrick Cahill SSCarpal Tunnel Group: General Forum Members Points: 4408 Visits: 1029 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 Veteran Group: General Forum Members Points: 236 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 Right there with Babe Group: General Forum Members Points: 737 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 Hall of Fame Group: General Forum Members Points: 3711 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: 278 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.