locking and unlocking mechanism

Hi All,

I am trying to implement a client program that can obtain record from MSSQL. I am using hibernate to do that.

So client A and client B will get record from DB server
both client A and B are on different machines

How can i prevent the situation that

ClientA get
ClientB get
ClientA update
ClientB update

In the database, i have a retrieve flag for each record. once the client get the record, it will update the record with the retrieve flag = true

Anyone can provide me advice on that? thanks a million

Have a google (or a search in these forums) for "optimistic locking" - this is techique usually used to solve the lost update problem. Also, have a read of the Hibernate documentation about versioning, which is Hibernate's optimistic locking implementation.