Design a Database for storing students’ grades

Problem

Imagine a simple database storing information for students’ grades. Design what this database might look like, and provide a SQL query to return a list of the honor roll students (top 10%), sorted by their grade point average.

Solution

In a simplistic database, we’ll have at least these three objects: Students, Courses, and courseEnrollment. Students will have at least the student name and ID, and will likely have other personal information.
Students:

• ID(INT)
• FirstName(VARCHAR(60))
• LastName(VARCHAR(60))
• Birthday(DateTime)
• [any other relevant student field information added...like contact info, etc]

Courses will contain the course name and ID, and will likely contain the course description, professor, etc.
Classes:

• ID(INT)
• ClassName (VARCHAR(50))
• ClassDescription (TEXT)
• ProfessorID(foreign key to professor table)

CourseEnrollment will pair Students and Courses, and will also contain a field for CourseGrade. We will assume that CourseGrade is an integer.
CourseEnrollment :

• ID(INT)
• StudentID(INT)
• ClassID(INT)
• Grade(Int)

Our SQL query to get the list of honor roll students might look like this:

SELECT StudentName, GPA
FROM (
  SELECT top 10 percent Avg(CourseEnrollment.Grade) AS GPA,
    CourseEnrollment.StudentID
  FROM CourseEnrollment
  GROUP BY CourseEnrollment.StudentID
  ORDER BY Avg(CourseEnrollment.Grade)) Honors
INNER JOIN Students ON Honors.StudentID = Students.StudentID

References 
http://tianrunhe.wordpress.com/2012/04/19/database-and-query-for-students-grades/