How to delete by criteria in hibernate?

Question

I have a student table and want to delete all students in a class.

So my sql query would look like:

delete from student where classId = 333 

How can I do this using hibernate with criteria?

I need this so I can put in one of my base classes to use by any DAO objects that extend from it. So I can make this generic across all of my DAO objects.

Currently I have created a generic method that will taken in the Student Object - calls the find method that uses the criteria to get the list and then I do a batch delete under one transaction as follows:

public boolean deleteByCriteria(Object deleteObject) {     List deleteObjectList = find(deleteObject);     if (deleteObjectList == null)         return false;     return deleteAll(deleteObjectList); }  public boolean deleteAll(List deleteObjectList) {     if (logger.isDebugEnabled()) {         logger.debug("Entered BaseSchoolRollBookDAO -> delete");         logger.debug("Object for batch deletion [" + deleteObjectList + "]");     }     boolean result = false;     Transaction tx = null;     // Get CurrentSession from HibernateUtils     Session session = HibernateUtils.getSession();     // Start transaction     tx = session.beginTransaction();      // Create new Criteria to be passed     try {         int flushCount = 0;         for (Object deleteObject : deleteObjectList) {             session.delete(deleteObject);             flushCount++;              if (flushCount % 20 == 0) {                 session.flush();                 session.clear();             }         }                     tx.commit();         result = true;     } catch (HibernateException e) {         logger.fatal("Exception in executing batch Delete query", e);         if (tx != null && tx.isActive())             tx.rollback();      }     return result; } 

Answer 1

For deleting use HQL which is the best option, I think, Criteria's main purpose is for only retrieving the data.
This one is with Criteria

  Student student = (Student ) session.createCriteria(Student.class)                     .add(Restrictions.eq("classId", classId)).uniqueResult();   session.delete(student); 

And this one is simple HQL query:

String hql = "delete from Student where classId= :classId"; session.createQuery(hql).setString("classId", classId).executeUpdate(); 

Answer 2

You can easily achieve by following simple hibernate as follows,

Session session=getSession();   String hql = "delete from Student where classId= :id";  session.createQuery(hql).setLong("id", new Integer(id)).executeUpdate(); 

for details refer