[英]Group by multiple columns : SQL
我有一张桌子:
我有一个查询给了我
我想要这样的东西:
用于上述结果的查询是:
select ucountry,sum(Males) Males,sum(females ) Females from (
select ucountry,
case when gender = 'M' then count(1) else 0 end as Males,
case when gender = 'F' then count(1) else 0 end as females
from testing.test_users
group by ucountry, gender
) a group by ucountry;
我绝对不是在这里做最好的事情。 大家觉得有什么更好的吗?
如果您要计算每个国家/地区的男性和女性人数:
select ucountry,
sum(case when gender = 'M' then 1 else 0 end) as males,
sum(case when gender = 'F' then 1 else 0 end) as females
from testing.test_users
group by ucountry
如果您使用的是PostgreSQL那么您也可以使用FILTER
select ucountry, COUNT(*) FILTER (WHERE gender = 'M') males,
COUNT(*) FILTER (WHERE gender = 'F') females from testing.test_users group by ucountry
您应该仅在ucountry列上应用GROUP BY 。 使用以下查询在SQL 服务器中获得预期结果:
SELECT
ucountry,
SUM(IIF(Name = 'M', 1, 0)) males,
SUM(IIF(Name = 'F', 1, 0)) females
FROM testing.test_users
GROUP BY ucountry
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