代码杂谈-SQL中的rank&row_number函数

两个函数细节记不住. 写个例子备注一下.

 select
no, name, score
, rank() over(partition by no order by score asc) rk1
, rank() over(partition by no order by score desc) rk2
, row_number() over(partition by no order by score asc) rn1
, row_number() over(partition by no order by score desc) rn2

from  values
 (1,'a',1), (1,'a', null),
 (1, 'b',2), (1, 'b',-2), (1, 'b',1)
 t (no, name, score)
;

结果

no	name	score	rk1	rk2	rn1	rn2
1	b	2	5	1	5	1
1	a	1	3	2	3	2
1	b	1	3	2	4	3
1	b	-2	2	4	2	4
1	a	\N	1	5	1	5