Java Data Manipulation with Hibernate

1. JDBC Overview

Why do we need a database? How does the interaction between a database and code work? What tools are used for different types of databases? You will learn all about this in this section!

Databases, DBMS

JDBC Introduction

JDBC API Components

DAO

Boilerplate Code Auto-Generation

Section 1 Summary

2. Fundamentals of Hibernate

This section will tell you how to set up and use Hibernate. You will learn how this framework works, what ORM is, and how to work with databases efficiently. You will also learn to write basic operations with a connected database, demonstrating your skills in practice!

Hibernate. ORM

Hibernate Config and Entities

Challenge: Entity Creation

Transactions and Session

Implementing DAO Pattern for our Program

Challenge: Implementing DAO

`query()` and `nativeQuery()`

Challenge: Query

Entity Relations and Cascade Types

Implementing the `Role` Entity

Challenge: Role Layers Implementation

Section 2 Summary

3. Final Touches

In this section, we will complete work on the project's foundation for employee management in the company. We will add the remaining operations and one more entity.

`update` operation for Employee and Department

Challenge: Department Layers Improvement

`Task` Entity Implementation

Understanding the Program's Functionality and Summarizing

What's next?

Challenge: Query

It's time to practice

In the previous chapter, we implemented 2 methods in the Employee service layer. We used queries to fetch the necessary data, and now you will have to do a similar task.

Your work will involve 4 classes:

DepartmentDaoImpl;
EmployeeDaoImpl;
DepartmentServiceImpl;
EmployeeServiceImpl.

You need to implement methods such as getAll and getEmployeesWithSalaryMoreThan(Double salary). To implement these methods, you will need to use either Query or NativeQuery, depending on what you choose to use, HQL or SQL. You will also need to use parameter substitution and return a list.

After you implement the methods, you can test your solution in the Main class, and then run the tests that I have written for you to check if you have implemented everything correctly.

Note
Don't forget to set up a connection to your database in hibernate.cfg.xml.

Link to the Task: GitHub

1. Use the code from the previous chapter as a hint.
2. Don't forget to change the data in hibernate.cfg.xml.
3. Don't forget about setting parameters in the query. This is done using the setParameter() method.
4. To obtain a list from the query, use the getResultList() method.
5. You can use main to test your solution.

// DepartmentDaoImpl

public List<Department> getAll() {
    Session session = null;
    List<Department> departments = null;

try {
        session = sessionFactory.openSession();

String hql = "FROM Department";

Query<Department> query = session.createQuery(hql, Department.class);

departments = query.getResultList();

} catch (Exception e) {
        System.out.println("Can't get departments" + e);
    } finally {
        if (session != null) {
            session.close();
        }
    }
    return departments;
}

//DepartmentServiceImpl

@Override
public List<Department> getAll() {
    return departmentDao.getAll();
}

//EmployeeDaoImpl

public List<Employee> getAll() {
    Session session = null;
    List<Employee> employees = null;
    try {
        session = sessionFactory.openSession();

String hql = "FROM Employee";

Query<Employee> query = session.createQuery(hql, Employee.class);
        employees = query.getResultList();
    } catch (Exception e) {
        System.out.println("Can't get Employees from the DB" + e);
    } finally {
        if (session != null) {
            session.close();
        }
    }
    return employees;
}

public List<Employee> getEmployeesWithSalaryMoreThan(Double salary) {
    Session session = null;
    List<Employee> employees = null;
    try {
        session = sessionFactory.openSession();

String hql = "FROM Employee WHERE salary > :salary";

Query<Employee> query = session.createQuery(hql, Employee.class);
        query.setParameter("salary", salary);
        employees = query.getResultList();
    } catch (Exception e) {
        System.out.println("Can't get Employees from the DB" + e);
    } finally {
        if (session != null) {
            session.close();
        }
    }
    return employees;
}

//EmployeeServiceImpl

@Override
public List<Employee> getAll() {
    return employeeDao.getAll();
}

@Override
public List<Employee> getEmployeesWithSalaryMoreThan(Double salary) {
    return employeeDao.getEmployeesWithSalaryMoreThan(salary);
}

Все було зрозуміло?

Секція 2. Розділ 8

Java Data Manipulation with Hibernate

Challenge: Query

It's time to practice

In the previous chapter, we implemented 2 methods in the Employee service layer. We used queries to fetch the necessary data, and now you will have to do a similar task.

Your work will involve 4 classes:

DepartmentDaoImpl;
EmployeeDaoImpl;
DepartmentServiceImpl;
EmployeeServiceImpl.

After you implement the methods, you can test your solution in the Main class, and then run the tests that I have written for you to check if you have implemented everything correctly.

Note
Don't forget to set up a connection to your database in hibernate.cfg.xml.

Link to the Task: GitHub

// DepartmentDaoImpl

public List<Department> getAll() {
    Session session = null;
    List<Department> departments = null;

try {
        session = sessionFactory.openSession();

String hql = "FROM Department";

Query<Department> query = session.createQuery(hql, Department.class);

departments = query.getResultList();

} catch (Exception e) {
        System.out.println("Can't get departments" + e);
    } finally {
        if (session != null) {
            session.close();
        }
    }
    return departments;
}

//DepartmentServiceImpl

@Override
public List<Department> getAll() {
    return departmentDao.getAll();
}

//EmployeeDaoImpl

public List<Employee> getAll() {
    Session session = null;
    List<Employee> employees = null;
    try {
        session = sessionFactory.openSession();

String hql = "FROM Employee";

public List<Employee> getEmployeesWithSalaryMoreThan(Double salary) {
    Session session = null;
    List<Employee> employees = null;
    try {
        session = sessionFactory.openSession();

String hql = "FROM Employee WHERE salary > :salary";

//EmployeeServiceImpl

@Override
public List<Employee> getAll() {
    return employeeDao.getAll();
}

@Override
public List<Employee> getEmployeesWithSalaryMoreThan(Double salary) {
    return employeeDao.getEmployeesWithSalaryMoreThan(salary);
}

Все було зрозуміло?

Секція 2. Розділ 8