根据 MySQL 中的分数串联学生

Question

表格scoretable:

id	name	score
101	L	10
101	M	9
101	N	10
102	O	10
102	X	10
103	P	8
104	Q	9
104	R	8

输出：

id	first	second
101	L,N	M
102	O,X
103	P
104	Q	R

下面是我的解决方案，我为同一 ID 获取多行。我的解决方案：

with
t1 as(select ID, name, Score, dense_rank() over(partition by ID order by Score desc) as rnk from scoretable),
t2 as(select t1.id, (case when t1.rnk=1 then string_agg(t1.name,' ') end) as first  from t1 group by t1.id,t1.rnk),
t3 as(select t1.id, (case when t1.rnk=2 then string_agg(t1.name,' ') end) as second from t1 group by t1.id,t1.rnk),
t4 as(select t1.id, (case when t1.rnk=3 then string_agg(t1.name,' ') end) as third  from t1 group by t1.id,t1.rnk)

select distinct t1.id,t2.first,t3.second,t4.third
from t1,t2,t3,t4
where t1.id=t2.id and t2.id=t3.id and t3.id=t4.id 
group by t1.id,t2.first,t3.second,t4.third
order by t1.id;

Answer 1

排名计算正常。但是使用条件聚合而不是三个连接来构建结果：

with cte as (
    select id
         , name
         , dense_rank() over (partition by id order by score desc) as dr
    from t
)
select id
     , group_concat(case when dr = 1 then name end separator ', ') as `first`
     , group_concat(case when dr = 2 then name end separator ', ') as `second`
     , group_concat(case when dr = 3 then name end separator ', ') as `third`
from cte
where dr <= 3
group by id

根据 MySQL 中的分数串联学生

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