Usage of transactions?

Database transactions are important, you either want the whole set of updates to happen or none of them. As an example, if you are transferring money from one account to another. One account needs to be debited and the other credited, and both changes need to happen for the transaction to be correct.

hi Matthew Francis , we used transaction with our code in java as shown in my code below

 @Override
    public void save(Category category) {
        // Open a session
        Session session = sessionFactory.openSession();

        // Begin a transaction
        session.beginTransaction();

        // Save the category
        session.saveOrUpdate(category);

        // Commit the transaction
        session.getTransaction().commit();

        // Close the session
        session.close();
    }

Sometimes in a database a set of changes need to happen as a single unit. A good example of this would be a bank transaction between two accounts. You want the withdrawal from one account to happen along with the deposit to the other but don't want other things to happen to the account to happen in the middle, like another withdraw from the first account leaving insufficient funds, or an error in updating the second causing the money to vanish. This is where transactions come in. They allow you to create a set of changes to happen as one, and the changes aren't actually made until you are finished and ready to commit them.