mysql - 同一列上多个条件的联合结果

Question

我想根据具有多个 where 条件的单个列来选择两列数据。

SELECT country.countryname,COUNT(users.uid) as cnt
FROM users
JOIN country
ON users.country = country.countrycode
WHERE users.useractivated = 1 AND users.status = 'on'
GROUP BY users.country
ORDER BY cnt DESC
LIMIT 30

此查询为我提供了主要的 cnt 列。现在我想要一个额外的 cnt2 列

根据以下条件选择

users.status <> 'on'

但仅适用于之前主要选择的 30 个国家/地区。

所以输出看起来像

+----------------+-------+---------+
|   countryname  |   cnt | cnt2    |
+----------------+-------+---------+
| USA            | 1012  |  12     |
| CANADA         | 1125  |  135    |
| ...            | ...   |  ...    |
+----------------+-------+---------+

我怎样才能做到这一点？

Answer 1

将 SUM 与 if 结合使用

SUM(IF(users.status = 'on', 1, 0)) AS cnt

或

SUM(IF(users.status <> 'on', 1, 0)) AS cnt2

查询:-

SELECT country.countryname,
SUM(IF(users.status = 'on', 1, 0)) AS cnt,
SUM(IF(users.status <> 'on', 1, 0)) AS cnt2
FROM users
JOIN country
ON users.country = country.countrycode
WHERE users.useractivated = 1
GROUP BY users.country
ORDER BY cnt DESC
LIMIT 30