Identify the No of days between job status

The above table represents the status of a jobnumber from order entery to completion. In this case for performance mprovement if we need to identify the number of days it has taken between each status

drop table #temp
delete from tbltulsaopkpi
create table #temp( id int identity , lotno varchar(30), jobDate datetime, status varchar(5) )
insert into #temp
select jobnumber, date,jobstatus
from tbltransjobstatus where jobnumber = 'A8000160-1'
--select * from #temp
declare @ctr int, @jobstatus varchar (3), @lotno varchar(20)
SELECT @ctr = count(id) FROM #temp
declare @olddate datetime, @newDate datetime
declare @i as int, @noDays as int
set @i= 1
set @noDays = 0
WHILE @i <= @ctr -- - 1 >= 0
BEGIN
if @i = 1 --or @i =@ctr
BEGIN
select @oldDate = jobdate, @lotNo = lotno, @jobStatus = status
from #temp
where id = @i
-- select @oldDate, @lotNo, @jobStatus, 0
insert into tbltulsaopkpi values
(@lotno,@jobstatus,0)
END
else
BEGIN
select @newDate = jobdate, @lotNo = lotno, @jobStatus = status
from #temp
where id = @i
set @noDays = datediff(day,@oldDate, @newDate)
- (datediff(ww,@oldDate, @newDate + case when datename(dw,@oldDate) = 'sunday' then 1 else 0 end))
- (datediff(ww,@oldDate, @newDate + case when datename(dw,@newDate) = 'saturday' then 1 else 0 end))
- (datediff(ww,@oldDate, @newDate + case when @newDate not in (select date from tblholiday where finyr = dbo.ufgetfinyr(@newDate)) then 1 else 0 end))
insert into tbltulsaopkpi values
(@lotno,@jobstatus,@noDays)
-- select @newDate, @lotNo, @jobStatus, @noDays
set @oldDate = @newDate
END
set @i = @i + 1
-- create table tbltulsaopkpi (
-- lotno varchar(20),
-- jobstatus varchar(5),
-- NoofDays int
-- )
END
-- select * from tbltulsaopkpi

--writter by marquerite