语法格式：row_number() over(partition by 分组列 order by 排序列 desc)
row_number() over()分组排序功能：
在使用 row_number(...into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(1,'a',10,8000);
insert into TEST_ROW_NUMBER_OVER...into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,'c',14,3000);
insert into TEST_ROW_NUMBER_OVER...（无分组）
select id,name,age,salary,row_number()over(order by salary desc) rn
from TEST_ROW_NUMBER_OVER t...rank
from TEST_ROW_NUMBER_OVER t
结果：
再一次排序：找出每一组中序号为一的数据
select * from(select id,name,age,salary,row_number
