Jsp/jdbc - Tomcat

Question

My requirement is once i issue a request from my jsp (the request is a sql query) it has to hit the database and should
return the number of affected row but should not commit it . In the next request from jsp the user will either hit
commit button or rollback button and based on the request it will either commit or rollback .In order to acheive this i
believe i have use the same connection object for both request.
I know http is stateless and i have to use the same connection object for both the request .
1) How can i use the same connectionobject in both request.?
2) What if the user did not click commit or rollback button . How can i expire the connection object that was opened during first request

Answer 1

I think you might want to read up on this on google:
optomistic concurency sql
I think the best solution is to get/use/close your connection as fast as possible (in a try/catch/finally block) within the same function.
In your database table, add a new column called 'version'. Each time someone updates a record in the table, increase the value of version by one for that record.
Now, in your design, read the record (including version number), display it to the user. Later, when the user clicks the update button, see if the version number has changed when you go to update.
If so, inform the user that the record has changed in the meantime. Usually, end users work on different records and seldom the same record at the same time so the collision doesnt occur often.
Example
sql= update person set firstName='john' where person_id=434 and version=34
The above will return a value of '1' if it was updated, '0' if it wasn't.
Note there is no need to rollback with this method.
Transaction advice:
Use a transaction if:
1) You are updating/inserting/deleting more than one record in a table and need to rollback if any one record update/insert/delete fails (or the version number shows it was changed per the above example).
2) you need to query one table and update the same table or some another table and want to ensure no records were changed between the query and update (treat them as an atomic operation).
3) you need to create more than one query to query several tables and want to ensure no data was changed in any table while doing the queries.
No tranaction if:
1) you query more than one table using one sql statement (a join).
See also database section at http://www.javapractices.com/home/HomeAction.do