示例代码：
t = table(2022.07.04T00:00:00 2021.07.04T00:00:00 2022.07.04T00:00:00 2021.07.04T00:00:00 as time, `A`A`B`B as sym, 1.0 2.0 3.0 4.0 as openPrice)
def groupByTime(time) {
return substr(string(time), 5)
}
select time, sym, openPrice, ratios(openPrice) - 1 as ratios from t context by sym, groupByTime(time) as time csort time