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After adding the data and before you get this data for testing, you need to run the code:

session.flush();session.clear();

• "Flush" - forcibly writes all entities to the database.
• "Clear" - (clear 1st level cache) Completely clear the session. Evict all loaded instances and cancel all pending saves, updates and deletions

Why is this so important? Since there may be cases when we have in the persistent state two objects with the same id

// 1. insert/createUser userCreated = getUserByDefault();int idUserForUpdate = userRepository.createUser(userCreated);// 2. flush and clearflushAndClearSession();// 3. get data and assertUser userExpected = UserUtil.createUserWithoutId("second", "second", "second", "123");userExpected.setId(idUserForUpdate);userRepository.updateUser(userExpected);User actualUser = userRepository.getUser(idUserForUpdate);assertThat(actualUser, equalTo(userExpected));

WithoutflushAndClearSession() will throw:org.hibernate.NonUniqueObjectException: A different object with the same identifier value was already associated with the session

When you run tests in the console, the display sql using lib "p6spy" - with params in sql:)

The log filetest.log contains the sql requests generated using standard tools of hibernate.

This strategy is used if we want to share Java code between entity classes.
Use@MappedSuperclass in base class

see dir:/src/test/java/org/example/inheritance/no_inheritance

The Single Table strategy creates one table for each class hierarchy. This is also the default strategy chosen by JPA if we don’t specify one explicitly.

see dir:/src/test/java/org/example/inheritance/single_table

The Table Per Class strategy maps each entity to its table which contains all the properties of the entity, including the ones inherited.
Like "No inheritance"

see dir:/src/test/java/org/example/inheritance/table_per_class

Using this strategy, each class in the hierarchy is mapped to its table.

see dir:/src/test/java/org/example/inheritance/joined

• Without cascade:
  see dir:/src/test/java/org/example/entity/relations/OneToMany/JoinColumn/NotCascade