Question

我有以下SQL查询：

SELECT 
    COUNT(CASE WHEN u.account_new = 1 THEN u.user_id END) AS new_user, 
    COUNT(u.user_id) AS all_users, 
    c.country_name AS country 
FROM users u, countries c 
WHERE u.country_id = c.country_id 
GROUP BY u.country

显示按国家/地区分组的新用户和总用户数。我想排除新用户数为零的行，但我不确定如何在上面的SQL中执行此操作。目前我正在使用PHP跳过它们，但认为可能有更好的方法来编写查询。

欢迎任何建议。

Answer 1

使用此：（注意HAVING条款）

SELECT 
    COUNT(CASE WHEN u.account_new = 1 THEN u.user_id END) AS new_user, 
    COUNT(u.user_id) AS all_users, 
    c.country_name AS country 
FROM users u, countries c 
WHERE u.country_id = c.country_id 
GROUP BY u.country 
HAVING COUNT(CASE WHEN u.account_new = 1 THEN u.user_id END) > 0

Answer 2

这包括为计算新用户提供更好的阅读改进：

SELECT 
    SUM(u.account_new=1) AS new_user, 
    COUNT(u.user_id) AS all_users, 
    c.country_name AS country 
FROM users u, countries c 
WHERE u.country_id = c.country_id 
GROUP BY u.country 
HAVING SUM(u.account_new=1)>0

排除count为零的MySQL结果行

2 个答案: