InfluxDB的WHERE子句中，不支持使用 OR 来指定不同的time区间

issues:https://github.com/influxdata/influxdb/issues/7530

使用子查询

Select mean(*) from 
(select * from channel where (time > '2017-05-01 13:00:00' and time < '2017-05-01 15:00:00') ), 
(select * from channel where (time > '2017-05-01 18:00:00' and time < '2017-05-01 19:00:00') )
GROUP BY time(20m)fill(none);