import java.sql.*;
import simpledb.remote.*;
import java.util.*;
import java.io.*;

public class CalculateGPA {
    public static void main(String[] args) {
		Connection conn = null;
		try {
			Driver d = new SimpleDriver();
			conn = d.connect("jdbc:simpledb://localhost", null);

			Reader rdr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(rdr);
			System.out.print("Enter student name: ");
			String sname = br.readLine().trim();

			Statement stmt = conn.createStatement();
			String qry = "select sid from STUDENT where sname='" + sname + "'";
			ResultSet rs = stmt.executeQuery(qry);
			if (!rs.next()) {
				System.out.println("No such student");
				return;
			}
			int sid = rs.getInt("sid");
			rs.close();

			String qry2 = "select Points from ENROLL, GRADEPOINTS where Grade=LetterGrade and studentid=" + sid;
			ResultSet rs2 = stmt.executeQuery(qry2);
			int numcourses = 0;
			float totalpoints = 0;
			while (rs2.next()) {
				totalpoints += rs2.getInt("Points");
				numcourses++;
			}
			rs2.close();
			conn.close();

			if (numcourses == 0)
				System.out.println("No courses taken");
			else
				System.out.println("GPA = " + totalpoints/(10 * numcourses));
		}
		catch(Exception e) {
			e.printStackTrace();
		}
		finally {
			try {
				if (conn != null)
					conn.close();
			}
			catch (SQLException e) {
				e.printStackTrace();
			}
		}
	}
}