how to calculate number of leap years between two dates in t-sql?

Question

I am doing report in SSRS, I need dataset column for calculating the number of leap years between two dates in t-SQL. I found the function for single input parameter whether it is the leap year or not but for my requirement two parameters in function or any t-SQL statement.

Thanks..waiting for anybody reply

Answer 1

DECLARE @year int
SET @year = 2008
if (((@year % 4 = 0) AND (@year % 100 != 0)) OR (@year % 400 = 0))
print 'Leap year'
ELSE
print 'No'

Answer 2

It's not clear what you want to do with the first and last year depend on your date parameters. Here is an example how to do it with the recursive query:

with cte as
(
     select YEAR('1900-01-01') as [year]
     union all
     select [year] + 1
     from    cte   
     where   [year] + 1 <= YEAR('2100-01-01')
 )
 SELECT COUNT(*)
 FROM cte WHERE
           ([YEAR]%4=0) AND (([YEAR]%100<>0) OR ([YEAR]%400=0))
 OPTION(MAXRECURSION 1000)

SQLFiddle demo

Answer 3

Hope this too works.

DECLARE @X INT = 1590
DECLARE @Y INT = 1603

DECLARE @COUNT INT = 0,@Z INT = @X

WHILE (@X <= @Y)
BEGIN
    SET @COUNT = @COUNT + 
                (CASE   WHEN (@X%4 = 0 AND @X%100 !=0) OR @X%400 = 0 
                        THEN 1 
                        ELSE 0 END)
    SET @X = @X + 1
END

SELECT @Z BEGIN_YEAR,@Y END_YEAR,@COUNT NO_OF_LEAP_YEARS

Result

Answer 4

I thought, will add as another answer.

DECLARE @A DATE = '2008-03-23',
    @B DATE = '2012-04-20'

DECLARE @AM INT,@AY INT,@BM INT,@BY INT
SET @AM = DATEPART(MONTH,@A),   --3
    @AY = DATEPART(YEAR,@A),    --2008
    @BM = DATEPART(MONTH,@B),   --4
    @BY = DATEPART(YEAR,@B)     --2012

DECLARE @COUNT INT = 0

WHILE (@AY <= @BY)
BEGIN
    SET @COUNT = @COUNT + 
                (CASE   WHEN (@AY%4 = 0 AND @AY%100 !=0) OR @AY%400 = 0 
                        THEN 1 
                        ELSE 0 END)
    SET @AY = @AY + 1
END

SET @COUNT = @COUNT + CASE WHEN @AM >= 3 THEN -1 ELSE 0 END

SELECT @A BEGIN_DATE,@Y END_DATE,@COUNT NO_OF_LEAP_YEARS

As I dont have an instance of sql server available now,I did not test the code..But you will get the an idea about what I was trying to achieve. I declared @BM, in case you want to do the checking with the end month too..

Answer 5

Here's a sql function based on some of the answers above that should do this -

CREATE FUNCTION [dbo].[LeapDayCount]
(
    @StartDate as datetime,
    @EndDate as datetime
)
RETURNS int as
BEGIN

    DECLARE @StartYear int
    DECLARE @EndYear int
    DECLARE @Year int

    SELECT @StartYear = YEAR(@StartDate)
    SELECT @EndYear = YEAR(@EndDate)

    DECLARE @Count int

    SET @Count = 0

    SET @Year = @StartYear

    WHILE (@Year <= @EndYear)
    BEGIN
        SET @Count = @Count + 
                    (CASE WHEN (@Year%4 = 0 AND @Year%100 !=0) OR @Year%400 = 0 
                            THEN 1 ELSE 0 END)

        SET @Year = @Year + 1
    END

    --remove one leap day if start date is a leap year but after february
    IF ((@StartYear%4 = 0 AND @StartYear%100 !=0) OR @StartYear%400 = 0) AND MONTH(@StartDate) > 2 SET @Count = @Count -1

        --remove one leap day if end date is a leap year but less than 29th Feb
    IF ((@EndYear%4 = 0 AND @EndYear%100 !=0) OR @EndYear%400 = 0) AND (MONTH(@EndDate) = 1 OR (MONTH(@EndDate) = 2 AND DAY(@EndDate) < 29)) SET @Count = @Count -1

RETURN @Count
END

Answer 6

An improvement on the original answer

This has 2 improvements

• Fixed a bug relating to subtracting -1 when a start date is after feb EVEN when the start year is not a leap year
• Also the -1 function at the bottom should check the original start month NOT the changing 1.

 CREATE FUNCTION riskstore.GetLeapYearCount (@Start Date, @End Date) RETURNS INT AS BEGIN DECLARE @StartMonth INT = DATEPART(MONTH,@Start) DECLARE @StartYear INT = DATEPART(YEAR,@Start) DECLARE @OriginalStartYear INT = DATEPART(YEAR,@Start) DECLARE @EndMonth INT = DATEPART(MONTH,@End) DECLARE @EndYear INT = DATEPART(YEAR,@End) DECLARE @COUNT INT = 0 WHILE (@StartYear <= @EndYear) BEGIN SET @COUNT = @COUNT + (CASE WHEN (@StartYear%4 = 0 AND @StartYear%100 !=0) OR @StartYear%400 = 0 THEN 1 ELSE 0 END) SET @StartYear = @StartYear + 1 END SET @COUNT = @COUNT + CASE WHEN @StartMonth >= 3 AND ((@OriginalStartYear%4 = 0 AND @OriginalStartYear%100 !=0) OR @OriginalStartYear%400 = 0) THEN -1 ELSE 0 END RETURN (@COUNT) END 

Answer 7

Number of leap days between two dates.

DECLARE
    @StartDate DATETIME = '2000-02-28',
    @EndDate DATETIME = '2017-02-28'

SELECT ((CONVERT(INT,@EndDate-58)) / 1461 - (CONVERT(INT,@StartDate-58)) / 1461)

-58 to start counting from 1st March 1900 and / 1461 being the number of days between 29th Februaries. NOTE: in Excel, the -58 would be -60 as 1st Jan 1900 in Excel is day 1 but in SQL is day zero and SQL doesn't recognise 29th Feb 1900 whereas Excel does. ALSO NOTE: This formula will go wrong every 400 years as every 400 years we skip a leap year. Hope this helps someone.