Hi All,

I am child on Hiberate. I read the tutorial. But, I have a question. Please see the following example:

1. Assume, there is a table, called customers.
2. The table contain a field, called age.
3. Now, I want to change the age to 10. The coding is:

tx = session.beginTransaction();
Customer customers=session.load(Customer.class, new long(1));
customer.setAge(customer.getAge()+1);
tx.commit();

I don't know, when "txt.commit()" statement is executed, Hibernate framework why know the customer's age need to update?

Thanks.

Liu Ming

when hibernate retrieves an object from the database, it stores a copy( called snapshot) and gives you another copy(but still hold a refrence to it).

so when you call commit, it compares the copy it gave it to you with the copy it has(i.e with snapshot).
since you have modified the copy given to you, there will be difference between these two. So hiberanate will do an update.

This is called automated dirty checking. If you do a search for it, you will find a lot of resources.

Thanks a lot.

I understand now. I will do more research.

Liu Ming