DECLARE @FromDate DATETIME = '2019-02-28', @ToDate DATETIME = '2020-02-26',
@diff_year_temp int, @diff_year int,@diff_year_frac float,@ToDateDays float,@FromDateDays float,@y_to int,@y_from int,@diff float,
@FromDec float,@JanTo float,@JanToFrac float,@FromDecFrac float,@ToDateplusone datetime,@FromplusToyear datetime
set @diff_year_temp=datediff(year,@FromDate,@ToDate)
set @FromplusToyear=case when DATEPART(day,@FromDate)=29 and datepart(month,@FromDate)=2 then dateadd(day,1,dateadd(year,@diff_year_temp,@FromDate)) else dateadd(year,@diff_year_temp,@FromDate) end
set @ToDateplusone=dateadd(day,1,@ToDate)
set @y_to = datepart(year,@ToDate)
set @y_from=datepart(year,@FromDate)
set @FromDec=datediff(day,@FromDate,cast(CONCAT(@y_from,'-12-31') as date))+1
set @JanTo=datediff(day,cast(CONCAT(@y_to,'-01-01') as date),@ToDate)+1
set @ToDateDays = DATEDIFF(day, cast(@y_to as char(4)), cast(@y_to+1 as char(4)))
set @FromDateDays = DATEDIFF(day, cast(@y_from as char(4)), cast(@y_from+1 as char(4)))
set @FromDecFrac=@FromDec/@FromDateDays
set @JanToFrac=@JanTo/@ToDateDays
set @diff_year=case when @ToDateplusone >= @FromplusToyear then @diff_year_temp else @diff_year_temp-1 end
set @diff_year_frac=case when @ToDateplusone >= @FromplusToyear then datediff(day,@FromplusToyear,@ToDateplusone)/@ToDateDays else @JanToFrac+@FromDecFrac end
set @diff=@diff_year+@diff_year_frac
select @diff