mysql语法查询

Question

这段代码不会编译，也不会是神奇的SQL Server所做的。有人可以指出错误吗。而且，这是hw，但是赋值是sql-version不可知的，所以它真的没关系。感谢。

SELECT courseNo, section,
SELECT (
  count( * )
  FROM registration, students
 WHERE registration.idno = students.idno
)
FROM registration, students;

Answer 1

SELECT courseNo, section, count(*) as [count]
FROM registration, students 
WHERE registration.idno = students.idno 
group by courseNo,section