mysql syntax query

This code won't compile开发者_高级运维, or whatever it is that the magical sql server does. Could someone point out the error please. And ya, this is hw but the assignment is sql-version agnostic so it really doesn't matter. Thanks.

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

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