"Water to Explode" SQL statement review

The table structure of the course selection system is as follows:
Student table: Student (Sno,sname,sex,age,class)
Timetable: Course (cno,cname)
Selected timetable: SC (Sno,cno,score)
(1) Inquiry into the "database application" student number and name
(2) The name and number of students who have enrolled in 3 courses?

For example, do the following test data:

(1)

Select Sno,sname from student where Student.sno in (select Sno from SC where sc.cno= (select CNO from course where course.cn Ame= "Database Application"))

(2) Select Sno,sname from student where Sno in (select Sno from SC GROUP by SNO have count (sno) = 3)

"Water to Explode" SQL statement review