[T-SQL] Different methods to find leap year

Method 1 : General method

declare @year int
set @year=2000

select
case
when @year%400=0 then 1
when @year%100=0 then 0
when @year%4=0 then 1
else 0
end as is_leap_year
Method 2 : Find if the day difference between Jan 01 of this year to Jan 01 of next year is 366

declare @year int
set @year=2000

select
case
when datediff(day,DATEADD(year,@year-1900,0),DATEADD(year,@year-1900+1,0))=366 then 1
else 0
end as is_leap_year
Method 3 : Find if the day difference between Feb 01 to Mar 01 of this year is 29

select
case
when datediff(day,dateadd(month,1,DATEADD(year,@year-1900,0)),dateadd(month,2,DATEADD(year,@year-1900,0)))=29 then 1
else 0
end as is_leap_year
Method 4 : Find if the 60th day of this year falls in February last day (Feb 29)

declare @year int
set @year=2000

select
case
when day(dateadd(day,59,DATEADD(year,@year-1900,0)))=29 then 1
else 0
end as is_leap_year