Hi,

I have a general question about the the table relation.

Suppose I have two tables A & B and there is no relation between them in database.
Even in the generated .hbm file also there is no relationship.

But, if I manually put a "one to many" relation between table A & B in the .hbm file and entity class, will it work ?
Can I join the tables using HQL ?


Thanks in Advance,
Anish

No, it won't work without changing the database (if that's what you are asking).

Hibernate needs to store the information about the relationship between the two tables somewhere. It might be some column(s) on one of the tables or a joining table.

Hibernate should be able to create the required column(s) or table at startup, if you set the property "hibernate.hbm2ddl.auto" to "update".

Cheers,
Davide

Hi,

Thanks for your reply.

In my scenario, the database is in production and maintaining by a third party, they won't allow us to make the relationships between the tables.

I thought if I can specify the required relations in .hbm and entity class (without modifying the database), I will be able to specify joins using Criteria/HQL in order to get the linked Entity class instances.

Is there any other way to achieve the same?

Thanks and Regards,
Anish

You might be able to write the HQL/Criteria query, but Hibernate will then convert it into an SQL one and it will execute it on the DB.

I don't see how this could work if you don't store the relationship on the DB in some way.

> In my scenario, the database is in production and maintaining by a third party, they won't allow us to make the relationships between the tables.

What kind of changes can you apply to the database? Can you create a new table?

Hi,

Thank you very much for your prompt reply.

We have got only read only access to the database.

So we cannot even execute a create table script !

Thanks & Regards,
Anish