两个表的 SQL 排名

Question

我有两个用户排名表。 表 rankingA 和 rankingB。 每个表都有列：

• user_id
• 点
• group_id

分数越高，用户/组的排名就越高...

现在我尝试获取我所在组的排名问题的组排名。 到目前为止，我有这个 SQL：

select sum(ra.points) as rapoints, sum(rb.points) as rbpoints from public.rankinga ra
LEFT JOIN public.rankingb rb ON ra.group_id=rb.group_id and ra.user_id=rb.user_id where
ra.group_id=200;

它返回第 200 组的rankinga 和rankinb 的分数。 我怎样才能得到小组的排名？我试过了： row_number() OVER (ORDER BY sum(rb.points) DESC) AS rankb 但得到了错误的结果。

我对 group_id 200 的预期结果是：

rapoints,rbpoints,rarank, rbrank
420,        10,     3,  same points as group_id 300 so rbrank 2 or 3

我怎样才能得到这个？

设置

CREATE TABLE rankinga
(
user_id bigint,
group_id bigint,
points integer
)
CREATE TABLE rankingb
(
user_id bigint,
group_id bigint,
points integer
)
insert into public.rankinga (user_id,group_id,points) values (1,100,120),(2,100,300),  (3,100,20),(4,200,300),(5,200,120),(6,300,600);
insert into public.rankingb (user_id,group_id,points) values (1,100,5),(2,100,3),(3,100,10),(4,200,2),(5,200,8),(6,300,10);

Answer 1

我想你想用union all、聚合和窗口函数来做到这一点。加入表可能会丢失行（如果用户在一个表中但不在另一个表中）或计数过多（如果您加入组）。所以这可能会做你想做的事：

select group_id, sum(rapoints) as rapoints, sum(rbpoints) as rbpoints,
       sum(rapoints) + sum(rbpoints) as points,
       dense_rank() over (order by sum(rapoints) + sum(rbpoints) desc) as ranking
from ((select ra.group_id, sum(ra.points) as rapoints, 0 as rbpoints
       from public.rankinga ra
       group by ra.group_id
      ) union all
      (select rb.group_id, 0, sum(rb.points) as rbpoints
       from public.rankingb rb
       group by rb.group_id
      )
     ) ab
group by group_id;

如果您只想选择一个组，请将其放入子查询（或 CTE）中，然后选择该组。

Here 是一个 SQL Fiddle。

编辑：

如果您只需要一组的结果，您仍然需要计算所有组的值。所以：

select ab.*
from (<above query here>) ab
where group_id = 200;