Hello,
Can we use database views instead of tables in hiberante. If yes then what is the way to do that??. I am using an Oracle database and we already have many view and we want to use that views in the new application too. We dont want to insert or update, delete using View as they are not insertable we just want to use them in searching cases so only for retrieval.Please reply me asap.

Regards,
Shoaib Akhtar

just use view name instead of table on the mapping file

Hello,
Now i know that i can use View for mapping too. But what is irriating me is the fact that hbm2java requires primary key but my view has no primary key and no column is unique either and hbm2java does not generate mapping file and complains that there should be primary key or id defined. Please help me asap

Regards,
Shoaib Akhtar

How do you prevent duplicates without a primary key?

Create the entry with all fields as members of the composite key. Now this assumes that it will be unique in this case. If not then you may have to use the ROWID as/in the key (if you can get access to it).

I think its not importent if values are unique in a view, a view is only a stored query in the database with a table mapping.

No, a View is a virtual table with all the implications. A "stored query" can be materialized in a Temporary table, some people confuse the two.

thats not so right a view is a virtual table based on a sql query whitch is stored in the database!

Of course. But it's still a real table, just virtual. It needs a primary key.

sorry thats not right, a view only need a primary key when it is update and insertable!

Every view should be update and insertable, thats why it is a table! Come on, don't learn the relational model from Oracle books ;)

The fact is we just won't support constructs like tables/views without an identifying set of atributes. This is pretty impossible for ORMs, because you can no longer identify which row an object represents.

Keep in mind that you can in extreme cases map all properties of a class, that is, all columns of a view/table as a composite key. This correctly reflects the primary key in a table/view without an explicit primary key declaration: All attributes together are the primary key.

(This doesn't mean a database will work correctly: Most allow duplicate rows, that is, they allow bags of tuples instead of sets. There goes data integrity again. In practice, it works "most of the time".)

:)

sorry dont learning by oracle, it's written in the 1999 and 2003 sql refrence and this says a view is only insert and updateable if it based on one table. Then your right it needs an primary key. The other way is to make a view over several tables to display a report for an user or things like this... And then is it not updateable! (ok if you use oracle it is updateable, but we want to use the standard...)

But thats not the fact, the importent thing is thats hibernate works fine

Keep in mind that SQL is not a relational language and the SQL standard has not much to do with relational databases. There is a huge difference between "should be", "is standardized" and "is available" in the database world. Always try to see what it really is. A view is a relation, with all implications, completely transparent to the application (that is, its the same as a base table). Just because the SQL guys couldn't figure out how to make it a relation doesn't mean it shouldn't be nor that it is not available.