SQL语句报错：缺失表达式

Question

SQL> select * from Students
  2  where Not Exists(select * from Courses（
  3  where Not Exists(select * from SC
  4  where SC.StudentID = Students,StudentID and SC.CourseID = Courses.CourseID));

为什么一直报错：缺失表达式

Answer 1

这是 点，不是 逗号

Students.StudentID

这个 括号也去了