Java.Hibernate.Beginner.How do you create a basic HQL query?

🔹 Step-by-step example:

Session session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();

// Basic HQL query: fetch all User entities
String hql = "FROM User";
List<User> users = session.createQuery(hql, User.class).list();

for (User user : users) {
    System.out.println("Username: " + user.getUsername());
}

tx.commit();
session.close();

🔹 Key points:
✅ FROM User is an HQL statement selecting the entire User entity — no need for SELECT if you want the whole object.
✅ session.createQuery(hql, User.class) creates a typed query returning List<User>.
✅ Always execute inside an active transaction when reading or modifying data.

🔹 Adding filtering with parameters:

String hql = "FROM User u WHERE u.username = :username";
User user = session.createQuery(hql, User.class)
                   .setParameter("username", "john")
                   .uniqueResult();

if (user != null) {
    System.out.println("Found user: " + user.getUsername());
}

🔹 What makes HQL powerful?

• You query entities and properties → not tables or columns.
• Hibernate translates HQL to database-specific SQL.
• It’s portable and works across supported databases without changing your queries.

✅ Key takeaway:
To create a basic HQL query:
1️⃣ Write an HQL string (e.g., FROM Entity).
2️⃣ Pass it to session.createQuery().
3️⃣ Execute it with list(), uniqueResult(), or other query methods.