Hi All,

Am new to hibernate, i have a simple question,

in the mapping file if we declare the one to many relations for tables, then to select values from both the tables, to select values from both the tables we need to write HQL with join or simply select all will select according to the one to many relation in the mapping file???


for example i have two tables table1 and table2,

in table one's mapping file, for the ID in table1 column i have given one to many relation to the table2, to select the values according to ID from both the tables, we need to write the HQl with Join or select all from table1 will fetch the values from table2 aslo??

Please clear my doubt........

Thanks,
vyrav.

Hi VYRav,
You just need to write "select from bean1(of table1)" and it will fetch all the data to the bean2(of table2) which is a member variable of bean1.
Hibernate internally manages the queries and reduces the code for you.This is the beauty of hibernate.
Regards
Shail[/i]

In fact, it might even be easier than doing an HQL query in this scenario.

Say a User has many Addresses. If I know the primary key of the User, I can just load the User directly.



Then, all of the associated addresses are available through that user isntance, so I could do somthing like this:



One thing I will say is that your Hibernate Session will need to be open as you loop through the addresses. Don't close your session too early, or you'll get a LazyInitializationException, and we hate those!

Here's a great little tutorial on mapping one to many relationships. If you're new to Hibernate, you'll find it really useful. Check out the link on How Hibernate Works as well.




http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=18mappingonetomanyassociations

Thank you guys, you cleared my doubt.

Always a pleasure!