假设您使用somedate-goes-here"的值限制某处的日期:

assuming you are limiting the dates somewhere using value of "somedate-goes-here":

update employee set totalcommissions = totalc
from
(
-------------------------------------
-- sum capped commissions by employee
-------------------------------------
select employeeID, sum(sum_commissions) as totalc from
      (
      ---------------------------------------
      -- make sure sum is capped if necessary
      ---------------------------------------
              select employeeID
              , case when sum_of_c > 100 then 100 else sum_of_c as sum_commisions
              from 
              (
              -----------------------------------------------
              -- get sum of  commissions per day per employee
              -----------------------------------------------
              select employeeID, sum(commission) as sum_of_c from sale
              where created > "somedate-goes-here"
              group by employeeID, day(created)
              ) as x
      ) as c
  group by employeeID
) y 
inner join employee on employee.employeeID = y.employeeID