By default, all new Connection objects are in autocommit mode. When autocommit mode is on, a COMMIT statement is automatically executed after each statement that is sent to the database server. To turn off autocommit mode, explicitly call Connection.setAutoCommit(false).

When autocommit mode is off the JDBC Driver implicitly starts a new transaction when the next statement is sent to the database server. This transaction lasts until the user issues a COMMIT or ROLLBACK statement. If the user has already started a transaction by executing setAutoCommit(false) and then calls setAutoCommit(false) again, the existing transaction continues unchanged. The Java™ program must explicitly terminate the transaction by issuing either a COMMIT or a ROLLBACK statement before it drops the connection to the database or the database server.