def close(self):
		'''关闭与数据库的连接'''
		if VERBOSE:
			print 'Database connection CLOSE.'
		self.conn.close()
def _exit_modes_beyond(self, thisMode):
        if not self.modeList: return
        while len(self.modeList) > thisMode + 1: 
            self.modeList.pop().exit()