无法使用 group by 合并 sql 中的两个查询

Question

select sum(total) from (
(select sum(team1_score) as total from country,match_results where country_name=team1 group by country_name as s1)
UNION ALL
(select sum(team2_score) as total from country,match_results where country_name=team2 group by country_name as s2)
);

Answer 1

尝试删除别名，即 as s1 和 as s2

Answer 2

别名应该在子查询之外； MySQL 可能认为您正在尝试（毫无意义地）为分组标准设置别名。

Answer 3

删除 select 中的第二个别名和 group by 的别名，并为

中的子查询分配一个专有名称

select sum(total) from (
  select sum(team1_score) as total 
  from country,match_results 
  where country_name=team1 
  group by country_name 
  UNION ALL
  select sum(team2_score) 
  from country,match_results 
  where country_name=team2 
  group by country_name 
) T

您应该使用显式内部联接

select sum(total) from (
   select sum(team1_score) as total 
   from country
   inner join match_results on  country.country_name=team1 and 
   match_results.team1=team1
   group by country_name 
UNION ALL
   select sum(team2_score) 
   from country
   inner join match_results on  country.country_name=team2 and 
   match_results.team2=team2
   group by country_name 
) T

无法使用 group by 合并 sql 中的两个查询

not able to make union of two queries in sql using group by

mysql

sql

group-by

having