sql按半小时统计

floor(4.4)  结果为4，浮点转整型

(DATE_FORMAT(PrtTime,'%H')     取小时h

DATE_FORMAT(PrtTime,'%i')　　取分钟m

(h*60 + m) /30 　　　　　　　　　取整数部分进行分类汇总

Select result,count(result) as resultTotal,floor((DATE_FORMAT(PrtTime,'%H') *60 + DATE_FORMAT(PrtTime,'%i'))/30) as groupHalfHour from degassing_facility_production_data where (prtTime >= '2020-01-16' and prtTime < '2020-01-18') group by result,groupHalfHour ;