将来自 2 个不同表的 2 个不同计数连接到 sql 中的一个表中答案

【问题标题】：Join 2 different counts from 2 different tables into one subtable in sql将来自 2 个不同表的 2 个不同计数连接到 sql 中的一个表中
【发布时间】：2022-11-20 04:18:51
【问题描述】：

我有一个问题，我想计算一个国家从个人和团体比赛中总共赢得了多少奖牌，这并不能给我带来不利的结果。到目前为止我已经设法想出了这个。

select distinct C.Cname as Country, count(i.medal) as Medals_Won
from individual_results as i, Country as C, participant as p 
where (i.Olympian = p.OlympicID and C.Cname = p.country) 

union 

select distinct C.Cname, count(r.medal) as medals_Won
from team_results as r, Country as C, participant as p, team as t
where (r.team = t.TeamID and t.Member1 = p.OlympicID and C.Cname = p.Country)


group by C.Cname
order by medals_won desc

enter image description here

但我得到了这个结果。

即使我运行这两段单独的代码，我也会得到想要的结果，即enter image description here

【问题讨论】：

标签： mysql sql

【解决方案1】：

您应该对按 cname 分组的每个子查询的联合结果求和

    select t.Cname , sum( t.Medals_Won)
    from (

        select  C.Cname as Country, count(i.medal)  Medals_Won
        from individual_results  i 
        inner join  participant  p  ON i.Olympian = p.OlympicID 
        inner join Country  C ON C.Cname = p.country
        group by C.Cname

        union 

        select distinct C.Cname, count(r.medal) 
        from team_results as r
        inner join team as t ON r.team = t.TeamID
        inner join  participant as p ON t.Member1 = p.OlympicID
        inner join Country as C ON C.Cname = p.Country
        group by C.Cname

    ) t 
    group by t.Cname
    order by t.medals_won desc

【讨论】：