MySQL Query for book cost of a class

Question

I just need a single MySQL line query for the following.

Lets say there are 2 simple tables: Class and Books<

Answer 1

Something like this:

select c.classId, sum(b.cost) as TotalCost,sum(c.students) as TotalStudents from books as b, class as c where b.classId = class.Id and c.Id = YourKnowClassId group by c.Id;