I'm using Hibernate 2.1.3. The documents describe how to use "components" to map a single table into two classes (eg User, Address).

I'm working with a legacy database that has two tables that have a one-to-one relationship however the second table has just one additional column and instead of mapping these as 2 classes, I'd like to map these two tables into one class. Consider a User table and UserDetail table where the UserDetail table only has a "phone" column. I would like to map this to a single User class that in addition to the members corresponding to the User table, has a "phone" member as well.

Thanks,
Sanjiv

In Hibernate3, you can use the <join> element. In Hibernate 2 this is not possible, you will have to use something like a hidden one-to-one association.

Michael,

Please could you elaborate on the solution for the "mapping 2 tables into one class" solution in Hibernate 2.1.x

I am using a legacy database and need to map two tables into a single class, it is also a one-to-one relationship. This is currently being done with a view which encapsulates a simple select with a join on primary keys.

I was hoping to move this join out to the hibernate mapping.

You mention ... in regards to the example from sjivan... does this mean wrap the UserDetail.Phone column in a class itself and then have it as a member of the User class?

I have many columns in both tables and so this would get quite clumsy...

Thanks

Sorry, my first post above was missing a paragraph? Here is it complete

Michael,

Please could you elaborate on the solution for the "mapping 2 tables into one class" solution in Hibernate 2.1.x

I am using a legacy database and need to map two tables into a single class, it is also a one-to-one relationship. This is currently being done with a view which encapsulates a simple select with a join on primary keys.

I was hoping to move this join out to the hibernate mapping.

You mention
in regards to the example from sjivan... does this mean wrap the UserDetail.Phone column in a class itself and then have it as a member of the User class?

I have many columns in both tables and so this would get quite clumsy...

Thanks

An other approach is to map the two tables to two calsses and make them looking as one by having a facade class above the two.

If you use a DAO pattern you could write a DAO for the facade in order to hide the two mapped classes from the business logic.

HTH
Ernst

ernst_pluess thanks for the help,

I have considered this as well and using views in the database... but both are moving the problem "out of" Hibernate. I was looking for a solution that I could configure in the mapping file.

Looks like Hibernate3 contains what I am really seeking...

http://www.hibernate.org/21.html#A26
http://blog.hibernate.org/cgi-bin/blosx ... /join.html

Thanks,
Miles