Selam
Netten ilk aşamada aşağıdaki bilgiyi buldum. Tabiiki daha geniş bilgide edinebilirsin. http://otn.oracle.com'u tavsiye ederim.
İyi Çlaışmalar...
The following SET command sets the isolation level to the desired level:
set transaction isolation level {1|3}
isolation level 1 prevents dirty reads. Isolation level 2 prevents un-repeatable reads. Isolation level 3 prevents phantoms. Isolation level 3 is required by ANSI standards. For MS SQL Server and Sybase, the default is isolation level 1.
To implement isolation level 3, MS SQL Server and Sybase apply HOLDLOCK to all the tables taking part in the transaction. In MS SQL Server and Sybase, HOLDLOCK, along with page-level locks, can block users for a considerable length of time, causing poor response time.
If the MS SQL Server or Sybase application implements ANSI-standard chained (implicit) transactions with isolation level 3, the application will migrate smoothly to Oracle because Oracle implements the ANSI-standard implicit transaction model, which ensures repeatable reads.
In a non-ANSI standard application, MS SQL Server and Sybase transactions are explicit. A logical transaction has to be explicitly started with the statement BEGIN TRANSACTION. The transaction is committed with a COMMIT TRANSACTION or rolled back with a ROLLBACK TRANSACTION statement. The transactions can be named. For example, the following statement starts a transaction named