Programatically alter db table

[pointertowhat]

I'm trying to write an update app which needs to modify a table in the embedded Derby Db, but I get

java.lang.IllegalArgumentException: node to traverse cannot be null!

The code concerned is:

Query q = this.entityManager1.createQuery("alter table jobrecords add column enginesize int not null default 0"); 

q.executeUpdate();

The actual sql is fine - I can execute it directly with no problems.

 

[timw]

What persistence framework are you using?

Tim

 

[pointertowhat]

Sorry, should have said - I'm using Hibernate.

 

[Diancecht]

Maybe using getNamedQuery instead od createQuery ...

But I'd first re-check the query itself

Cheers,
Dian

 

[snitin78]

As a good practice, you should not be trying to alter tables using Hibernate, lest you would invalidate the table mapping.
Even if what you are trying to do works, how are you planning to update the POJO (mapped object for the table) with the new
property?

IMO, you should use Hibernate's capability of dynamically creating/updating the schema at startup.

 

[pointertowhat]

I was planning to write a small update app, it will be started by the autorun feature on windows. It will connect with the database and modify the table required, then copy a new application jar to the system. This will have all the modified pojo's etc.

IMO, you should use Hibernate's capability of dynamically creating/updating the schema at startup.

I'm quite new to hibernate - how would I go about doing this without loosing the existing data?

 

[snitin78]

See if this helps

http://www.jroller.com/eyallupu/entry/hibernate_s_hbm2ddl_tool