oracle rank() over( partition by a order by c) as rn

oracle rank() over(partition by A order by A) 计算出安装A分组，后组内部进行排序，select A,rank() over( partition by A order by A) as rn ,A from tmp  自动为A分组后的-组内部进行排序产生一字段，1,2,3,4,5,6