def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def _resetExpect(self):
        self.previousExpectLine = ""
        if self._connection is not None and isinstance(self._connection.buffer, str):
            self.previousExpectLine = self._connection.buffer 
            self._connection.buffer = ""