SQL 排名怎么写？

select et.company_no as companyNo,et.building_no as buildingNo,et.energy_code as energyCode,se.name as energyName,et.cycle_type as cycleType,
DATE_FORMAT(et.cycle_start_date, '%Y-%m-%d') as cycleStartDate, DATE_FORMAT(et.cycle_end_date, '%Y-%m-%d') as cycleEndDate,
sum(et.sum_flow) as sumFlow

, b.building_name as itemName

from gm_sys_energy se, gm_reading_sum_building_2018 et
left join gm_building b on(et.building_no=b.building_no and b.status=1)
where et.energy_code=se.energy_code and et.company_no=se.company_no and b.building_no=et.building_no and b.status=1

group by et.building_no,et.energy_code,et.cycle_type
order by et.sum_flow desc