pgsql： row_number() over(partition by)按字段分组后，组内排序，各组生产一个rn行号，对标groupby分组不能满足需求时使用

select *,

row_number() over(PARTITION by 某某字段 order by 排序字段) as rn

from table

 

例子：

select * from

（

select *,

row_number() over(PARTITION by 某某字段 order by 排序字段) as rn

from table

）as t1

where t1.rn = 1