Is possible that someboy make a example with the diferents IsolationLevel and explain the use.
thanks
StartTransaction(IsolationLevel ......
Oracle Documentation says following about transaction isolation levels:
Read committed - This is the default transaction isolation level. Each query executed by a transaction sees only data that was committed before the query (not the transaction) began. An Oracle query never reads dirty (uncommitted) data. Because Oracle does not prevent other transactions from modifying the data read by a query, that data can be changed by other transactions between two executions of the query.
Serializable - Serializable transactions see only those changes that were committed at the time the transaction began, plus those changes made by the transaction itself through INSERT, UPDATE, and DELETE statements.
Read-only - Read-only transactions see only those changes that were committed at the time the transaction began and do not allow INSERT, UPDATE, and DELETE statements.
Read committed - This is the default transaction isolation level. Each query executed by a transaction sees only data that was committed before the query (not the transaction) began. An Oracle query never reads dirty (uncommitted) data. Because Oracle does not prevent other transactions from modifying the data read by a query, that data can be changed by other transactions between two executions of the query.
Serializable - Serializable transactions see only those changes that were committed at the time the transaction began, plus those changes made by the transaction itself through INSERT, UPDATE, and DELETE statements.
Read-only - Read-only transactions see only those changes that were committed at the time the transaction began and do not allow INSERT, UPDATE, and DELETE statements.