聚合不应出现在 UPDATE 语句的集合列表中。

Question

 create trigger upd_grade on Reports
for update,insert
as
    update Students
    set CreditHours=(select sum(CreditHours) from Courses where Cno in(
    select Cno from Reports where Reports.Grade>=60 and Reports.Sno in(
    select Sno from inserted)))where Students.Sno in(select Sno from inserted)

Answer 1

(select sum(CreditHours) from Courses where Cno in(
select Cno from Reports where Reports.Grade>=60 and Reports.Sno in(
select Sno from inserted)))

    定义个参数，接收这个sum的值，然后再update。