Maximum values per day from data with different dates
问题 I have data taken at different times on different days, for example: dateTimeRead(YYYY-MM-DD HH-mm-ss) rain_value(mm) air_pressure(hPa) 1/2/2015 0:00 0 941.5675 1/2/2015 0:15 0 941.4625 1/2/2015 0:30 0 941.3 1/2/2015 0:45 0 941.2725 1/2/2015 1:00 0.2 941.12 1/2/2015 1:15 0 940.8625 1/2/2015 1:30 0 940.7575 1/2/2015 1:45 0 940.6075 1/2/2015 2:00 0 940.545 1/2/2015 2:15 0 940.27 1/2/2015 2:30 0 940.2125 1/2/2015 16:15 0 940.625 1/2/2015 16:30 0 940.69 1/2/2015 16:45 0 940.6175 1/2/2015 17:00 0