def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def _lastExpect(self):
        constructLine = self.previousExpectLine
        if self._connection is not None and isinstance(self._connection.before, str):
            constructLine += self._connection.before
        if self._connection is not None and isinstance(self._connection.after, str):
            constructLine += self._connection.after
        return  constructLine