row_number rank 的区别

现有一张部门表e_department：

departmentid           departmentname         parentid

CREATETABLE e_department(departmentid           INT,departmentname       VARCHAR(50),parentid           INT)

row_number,rank使用：

select row_number() over(order  by parentid) as rownumber,--还可以用partition来分类  例如性别
rank() over(order by parentid) rank_number, 
dense_rank() over(order by parentid) as  denserank_bymber,
ntile(5) over(order by parentid) as ntilenum,--强制分段
parentid as deptid
from e_department  where parentid is  not null

结果：

一目了然了吧。

row_number ,rank,dese-rank 在Oracle中同样如此。