I have Strange requirement, I have to work on recordLocking functionality,
When User1 is lock the request and editing the request, Administrator can unlock the request and edit the same request, whenever admin unlocak the request user1 has to get a promt saying that Admin has locked your request , You can't further proceed the same request.
Could any one please come up with one trigger in java to find out whenever the table "REQUEST" fields "lockby" and "lockedtime" changes to null we have to get promt ..? Is there any provision in Struts or JDBC
If this is a web app, then a trigger is probably not the way to go. Web apps are request driven, so even if the data changes there is no way to push that change out a client.
From a web app, your only real route would be to poll the table to watch for changes. You could do this in the background using AJAX.
That aside, if this were my task, I'd ask the person who set it to explain why pessimistic locking is required in a web app in the first place. Its usually considered bad practice; web apps and RBDMSs are by their nature designed to support multiple concurrent users. Once you add pessimistic locking to the mix that behaviour goes. A better way might be some sort of weighted optimistic locking pattern, where those users in the admin role "win" when there is a version mismatch?