/**
  * Marks the Connection as closed, and notifies the pool that the pooled connection is available.
  * In accordance with the jdbc specification this Connection cannot be used after closed() is
  * called. Any further usage will result in an SQLException.
  *
  * @exception SQLException The database connection couldn't be closed.
  */
 public void close() throws SQLException {
   isClosed = true;
   pooledConnection.notifyListeners();
 }