mysql语法查询

Question

此代码无法编译，或者神奇的 sql 服务器所做的任何事情都无法编译。有人可以指出错误吗？是的，这是硬件，但分配与 sql 版本无关，所以这并不重要。谢谢。

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