CREATE FUNCTION dbo.IsLeapYear (@year INT)
RETURNS INT
AS
BEGIN
RETURN ISDATE(’02/29/’+ Cast(@year AS varchar(4)))
END

GO
SELECT dbo.IsLeapYear(2012)

Admittedly the next adjustment year is 2100 so many of us will not actually care about this but fact remains that we cannot just check if the year is divisible by 4.

This is why MS saw fit to put the function in to SQL so that developers do not have to worry about it. I think we should avoid re-inventing the wheel and check a date against what Microsoft has done for us (even in 2008 the functionality exists as it knows if there are 29 days if you ask it that question directly) hence I think it works to take one off 1st march and test if its 29 in SQL Server 2008 and use the function Pinal spoke of for 2012.

Personally I would always recommend using a date (calendar) table in your database ratherthan a date calculation as you allow not oly for leap years but also all other special dates, company financial year etc.

Check out this excerpt from wikipedia page

http://en.wikipedia.org/wiki/Leap_year

“most years that are evenly divisible by 4 are leap years…”

“…Some exceptions to this rule are required since the duration of a solar year is slightly less than 365.25 days. Years that are evenly divisible by 100 are not leap years, unless they are also evenly divisible by 400, in which case they are leap years. For example, 1600 and 2000 were leap years, but 1700, 1800 and 1900 were not. Similarly, 2100, 2200, 2300, 2500, 2600, 2700, 2900 and 3000 will not be leap years, but 2400 and 2800 will be.”

return @r
end

select dbo.fncLeapYear (getdate())

select 2012 % 4

returns 0

simple

The formula you have written is wrong. You have to check the century year as well as year divisible by 400.

Thanks
Sanjay

And well done to David for your excellent 2008 version. I really like what you did there. Whenever I see a bit of 2012 code I always wonder how to acheive the same thing in 2008 and its usually not too hard to work out but it is usually longer and slightly more difficult to follow. Yours isn’t in-fact it proves that sometimes new features are just there for the more obvious issues and not always better (like CONCAT – which is pretty simple to mimick in 2008).

(incidentally – Another approach would be to take one day off March 1st and see if it is 29)

Thanks to both of you.

Dave (are we collectively all SQL Dave?)

declare @Year int = 2012
select isdate(’2/29/’ + cast(@Year as char(4)))

Note that besides being very simple to read and understand, this works correctly for null, 2 digit years and all of the whole centuries too. Unlike some of the solutions I’ve seen, this one does not cause a divide-by-zero error when the year = 0. Most of this SQL is test cases. The real code is all on one short line.

;with TestData (Y) as (
select cast(null as int)
union select 0
union select 1
union select 2
union select 3
union select 4
union select 5
union select 48
union select 52
union select 1900
union select 1996
union select 1999
union select 2000
union select 2001
union select 2004
union select 2011
union select 2012
union select 2013
union select 2100
union select 987654321
)
select Y as [Year],
/*
Careful – According to SQL BOL,
ISDATE is deterministic only if you use it with the CONVERT function,
if the CONVERT style parameter is specified, and style is not equal to 0, 100, 9, or 109.
The return value of ISDATE depends on the settings set by
SET DATEFORMAT, SET LANGUAGE and default language option.
The date string may need to be formatted differently depending on your SQL server configuration.
This next column is the one that determines if the specified year is a leap year.
*/
isdate(’2/29/’ + cast(Y as char(4))) as IsLeapYear,
– This next column is unnecessary.
– It just shows that this works with 1 & 2 digit years
case when isdate(’2/29/’ + cast(Y as varchar(4))) = 1
then cast(’2/29/’ + cast(Y as varchar(4)) as date)
else null
end as LeapDay
from TestData
order by Y

DECLARE @year int
SET @year = 2012
if (((@year % 4 = 0) AND (@year % 100 != 0)) OR (@year % 400 = 0))
print ’1′
ELSE
print ’0′

Is it possible to work on SQl 2008, kindly suggest

I just try for other simple method to find leap year… Please check the below query.

/*

Declare
@FromYear as int
set @FromYear=’2012′

select
case when
((@FromYear/4.0) /cast (@FromYear/4 as varchar(5)))= 1 then ‘Leap Year’
else ‘Not Leap Year’ end

*/

http://beyondrelational.com/blogs/madhivanan/archive/2011/01/05/different-ways-to-find-out-a-leap-year.aspx