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✅ Short Answer You can reattach a detached object to a Hibernate session using either: session.update(detachedEntity) → reattaches directly; expects no conflicting persistent instance with the same ID in the session. session.merge(detachedEntity) → copies the detached entity’s state into a … Continue reading →

✅ Short Answer When you modify a detached object, changes happen only in Java memory — Hibernate does not track or persist those modifications, because the object is no longer associated with any session. 🔎 Detailed Explanation Once an object … Continue reading →

✅ Short Answer Transient: object exists in Java memory only, not yet saved to the database or associated with a session. Persistent: object is associated with an open Hibernate session, and changes are automatically tracked and saved. Detached: object was … Continue reading →

✅ Short Answer Session.refresh(entity) reloads the state of a persistent entity from the database, overwriting any in-memory changes with the latest data in the database. 🔎 Detailed Explanation When you load an entity into a Hibernate session, Hibernate keeps it … Continue reading →

✅ Short Answer Session.evict(entity) detaches a single specific entity from the current Hibernate session. Session.clear() detaches all entities in the session at once by clearing the entire persistence context. 🔎 Detailed Explanation Session.evict(Object entity) Removes the given persistent entity from … Continue reading →

✅ Short Answer Session.clear() detaches all persistent entities from the current Hibernate session, effectively resetting the persistence context.After calling clear(), the session no longer tracks changes to any previously managed entities. 🔎 Detailed Explanation Hibernate uses the persistence context (a … Continue reading →

✅ Short Answer You need flush() when you want to force Hibernate to immediately synchronize in-memory changes with the database within an open transaction — usually so that subsequent queries or database operations see the latest changes before you commit. … Continue reading →

✅ Short Answer No — when you call flush(), Hibernate executes the SQL statements immediately, so the updates are sent to the database once.When you later call commit(), it finalizes the transaction — it does not re-send updates, but makes … Continue reading →

✅ Short Answer Session.flush() synchronizes the state of the in-memory persistent entities with the database by executing pending SQL statements, but it does not commit the database transaction. 🔎 Detailed Explanation In Hibernate, when you make changes (insert, update, delete) … Continue reading →

✅ Short Answer Session.save() inserts a new object into the database; if the object has an existing identifier, it will throw an error or overwrite unexpectedly. Session.merge() updates an existing object or saves it if it doesn’t exist, even if … Continue reading →