School Exercise (JPQL)

1. Set up the data model as shown in the diagram below

2. Using JPQL to find solutions to the following challenges

Part 1

1. Create a ´Populate` class with a main method. In the main method create a method that can populate the database with data.

Part 2

1. Create a dao package and add a new interface called StudentDAO and add the following code to the interface:

    public interface IStudentDAO {
        // find all students in the system with the first name Anders
        List<Student> findAllStudentsByFirstName(String firstName);
   
        // find all students in the system with the last name And
        List<Student> findAllStudentsByLastName(String lastName);
   
        // find the total number of students, for a semester given the semester name as a parameter
        long findTotalNumberOfStudentsBySemester(String semesterName);
   
        // find the total number of students that has a particular teacher
        long findTotalNumberOfStudentsByTeacher(Teacher teacher);
   
        // find the teacher who teaches the most semesters
        Teacher findTeacherWithMostSemesters();
   
        // find the semester that has the fewest students
        Semester findSemesterWithFewestStudents();
   
        // find all students, encapsulated as StudentInfo
        StudentInfo getAllStudentInfo(int id);
    }
   

2. At the same location add a new class called StudentDAOImpl and implement the interface to the class with all the methods.

3. In the root of the project add a new class called Populate and add the following code to the class:

public class Populate {
    public static void main(String[] args) {
        EntityManagerFactory emf = HibernateConfig.getEntityManagerFactoryConfig();
        EntityManager em = emf.createEntityManager();

        try {
            em.getTransaction().begin();
            // populate the database with data
            em.getTransaction().commit();
        } finally {
            em.close();
        }
    }
}

1. Run the main method in the Populate class to populate the database with the students, teachers, and semesters.

2. All the methods in the StudentDAOImpl class should now be implemented using JPQL.

Part 3

1. Create a StudentInfo class with the following properties:
   • fullName
   • studentId
   • thisSemesterName
   • thisSemesterDescription
2. Add a public constructor that takes all the necessary arguments to initialize the properties.
3. Now create a method (using JPQL) with the following signature to return a list of all Students, encapsulated as StudentInfo.
   • public StudentInfo getAllStudentInfo(int id)

PS. Add the getAllStudentInfo method to the StudentDAO interface and implement it in the StudentDAOImpl class.

Part 4

1. Create a test class with a test method for each of the methods in the StudentDAOImpl class.

2. Run the test class and verify that all tests pass.

Good luck!