select *
from (select row_number() over(partition by t.project, opp.dfdw_2 order by t.imtime desc) rn, 2020 year, 2 period, 12301 subjectCode, t.project,opp.dfdw_2
from proc_voucheritem_2020 t
left join pre_oppprctr_dfdwmapping_2020 opp
on t.oppprctrid = opp.oppprctrid
where 1 = 1
and t.monat = 2
and t.mdm_prctr = '1043085'
and t.hkont like '123101%')
where 1 = 1
and rn = 1;
over 函数:
partition by 后面是分组字段
order by 后面是排序字段