Concurrent record update

[BOUTTE Sebastien]

Hi,

 

I have some questions about blocking concurrent update with multiple clients.

I have the following schema of transaction :

 

User A                                         User B 

1. SELECT * FROM TEST

                                                   2. SELECT * FROM TEST

                                                   3. UPDATE TEST SET .... WHERE TEST_ID = n

4. UPDATE TEST SET ..... WHERE TEST_ID = n

 

In this schema, two users are updating the same record but update from B is lost ....

How can i do that in my SessionBean, to throw an exception for user A when he tries to

update the record ?

I have read some articles about database isolation level and transaction level in EJB world

but i don't see how to apply them to my case.

 

Thanks for your help

 

Sebastien

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