def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
async def get_next(next_link=None):
            request = prepare_request(next_link)

            pipeline_response = await self._client._pipeline.run(request, stream=False, **kwargs)
            response = pipeline_response.http_response

            if response.status_code not in [200]:
                error = self._deserialize.failsafe_deserialize(_models.QueryFailure, response)
                map_error(status_code=response.status_code, response=response, error_map=error_map)
                raise HttpResponseError(response=response, model=error, error_format=ARMErrorFormat)

            return pipeline_response