如何使用lag函数查找sql server中相同列的连续行之间的差异

我一直在尝试下面的查询，但我得到了恒定的差异

with cte as 
(
select businessentityid,nationalidnumber,SickLeaveHours,LAG(sickleavehours) over (order by businessentityid) as PreviousRow
from HumanResources.Employee
)
select *,DIFFERENCE(sickleavehours,cte.previousrow) from cte

你能这样做吗？：

with cte as 
(
select businessentityid,nationalidnumber,SickLeaveHours,LAG(sickleavehours) over (order by businessentityid) as PreviousRow
from HumanResources.Employee
)
select *, sickleavehours - cte.previousrow as difference from cte