It is a big problem for me.

my project is a refactoring project to a old system.
in the old system, we create a table by each year.

such as: TBL_NEWS_2003, TBL_NEWS_2002

so when we need search in years, we use UNION to select from all table.

BUT how can i do this in hibernate??

I create a class named: News,
and , actually I must make a News.hbm.xml for it.
and i wrtie table name in the XML.

I need associate the New.class to multi-table
when i query some news, i can specify a tablename or modualname parameter to the session and get the same class from different table.

can i make myself understand?

I NEED HELP.

Unions are not doable AFAIK

Try to do this kind of mapping:
Create a News class, create News2002, News2003 as subclasses.
Map as table-per-concrete class (map News2002 and News 2003 but not News). And play with that.

This solution has many drawbacks, and probably don't be appropriate in your case.

Submit a request to JIRA for you initial feature, Gavin will tell you if you can expect that in a future Hibernate.

I don't know what's JIRA??
how can i contact Gavin to suggest my advice as below?

When one develop a website such as a news website.
It its very easy to consider making a generic News.class to
fit for all kinds of news.
eg. A news may have title, content, date ...

so we develop a News.class.
but we have different news, like entertaiment, sport, government, techinical .....

so, we must have dynamically mapping to News.class

News.class should associate to several *.hbm.xml file, each file figure to a table.
like News.sport.hbm.xml, News.entertaiment.hbm.xml

(May be we can specify the different table name just in the filename)

and the Configuaration can read all xml
and one can query News.class in all different table or only one table.

That's what i except mostly of the future hibernate.

CREATE VIEW AS ...

Well I don't understand your pb. You told me you where in a 1 table per year issue, and then you seems to have simple table-per-hierarchy will.

Map news then map subclasses of News (SportNews, etc..) as <subclass> of News. Hibernate auready do that.

JIRA is the issue tracking facility.
http://opensource.atlassian.com/projects/hibernate/secure/Dashboard.jspa or the left link in Hibernate web site.
But clarify your though before posting an enhancement request.


I'm not familiar with all DBMS but I'm not sure this kind of VIEW be updateable/ insertable.

Map your class to the current year table, and then just use createSQLQuery() to write your own custom union query to read from all tables.

This will work as long as you only want to add/update into the current year table and just need to read from the past.

Thank's max. Your advice solve part of my problem.

but the BIGGEST problem is, My recently year table is create by program automatic. I can not have a PO class to map it.

So I'd like to suggest to Hibernate group adding a dynamic table name mapping function.

by epbernard's method:
I use News.class' subclass SportNews, It's a good solution for the System
not creating table by program itself. It's fit for static tables.

I heard that Gavin King said a custom ClassPersister can deal with the dynamic table name problem.

But ... big trouble...

Common solution for this kind of problems are views.
It is possible to use system tables for metadata, stored procedures, query rewrite to make logical view of data.
But it is very common to ignore RDMS features and to handle logical view of data in application too :)

btw. this precise usecase is now solvable via the new "entity-name" feature in v22branch in hibernate cvs!

Look at the devel-mailing list for details ;)