Important JDBC Concepts

Transactions: Whenever a connection is created by using the JDBC, then by default it is in auto- commit mode. This means that SQL statement will be automatically committed immediately after it is executed and it is treated as a transaction. But imagine a situation where you want to execute a batch of statements, either they should commit at on go or they should get failed together. For this we need to disable the auto- commit mode by using the method:

con.setAutoCommit(false).

After setting the auto- commit as false, no SQL statement will be committed until we call the con.commit() method. If there arises any problem while committing then the set of statements will be rollback, without committing.

Logging: on the server--->logging--->JDBC.

By this we can enable JDBC logging and specify a log file name for the JDBC log.

Attributes of Logging:

1) Enable JDBC Logging: It determines whether the server has a JDBC log file.

2) JDBC Log File Name: It is the name of the log file.

Isolation: The isolation is needed when there are concurrent transactions. Concurrent transactions are transactions are transactions that occurs at the same time. In isolation one transaction does not interfere with another. For setting the isolation level for a JDBC transaction, use the

Connection.setTransaction(int level) method

By using the snapshot isolation level we can only see the snapshot of the data locked by other transactions when running from inside the transaction with snapshot isolation level.

Some of the transaction level are given below:

1). TRANSACTION_NONE

2). TRANSACTION_READ_UNCOMMITED

3. TRANSACTION_READ_COMMITTED

4. TRANSACTION_REPEATABLE_READ

5. TRANSACTION_SERIALIZABLE

By setting the isolation levels you are having an impact on the performance of the transaction. You can get the existing isolation level with:

getTransactionIsolation() method.

Concurrency: Database concurrency controls ensure that the transactions occur in an ordered fashion.

Concurrency control deals with the issue involved with allowing multiple people simultaneous access to shared entities.