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Notes on JDBC connections

• Autocommit behavior    The JDBC specification requires that, by default, a COMMIT is performed after each data modification statement. Currently, the client-side JDBC behavior is to commit (autocommit is true) and the server-side behavior is to not commit (autocommit is false). To obtain the same behavior in both client-side and server-side applications, you can use a statement such as the following:

  con.setAutoCommit( false );

  In this statement, con is the current connection object. You could also set autocommit to true.

• Connection defaults    From server-side JDBC, only the first call to getConnection( "jdbc:default:connection" ) creates a new connection with the default values. Subsequent calls return a wrapper of the current connection with all connection properties unchanged. If you set autocommit to false in your initial connection, any subsequent getConnection calls within the same Java code return a connection with autocommit set to false.

  You may want to ensure that closing a connection restores the connection properties to their default values, so that subsequent connections are obtained with standard JDBC values. The following code achieves this:

  Connection con = 
      DriverManager.getConnection("jdbc:default:connection");
  
  boolean oldAutoCommit = con.getAutoCommit();
  try {
       // main body of code here
  }
  finally {
      con.setAutoCommit( oldAutoCommit );
  }

  This discussion applies not only to autocommit, but also to other connection properties such as transaction isolation level and read-only mode.

  For more information about the getTransactionIsolation, setTransactionIsolation, and isReadOnly methods, see documentation on the java.sql.Connection interface.