Question

我正在尝试对以下内容运行查询：

用户表有id和is_paying。订阅表具有id，user_id和subscription_plan

我想获得具有subscription_plan = 81和is_paying ='Y'的用户的用户ID列表。我跑的时候

select count(distinct users.email) 
from users,subscriptions 
where subscription_plan_id=81 
and users.is_paying_customer = 'Y';

查询运行的时间太长，因为我不认为它将两个表连接在一起，我不确定如何执行此操作。有什么建议吗？

Answer 1

要获取用户列表，请删除COUNT。此外，您需要设置JOIN条件以将用户与订阅相结合：

select DISTINCT users.email 
from users JOIN subscriptions ON users.id = subscriptions.user_id
where subscription_plan_id=81 
   and users.is_paying_customer = 'Y';

Answer 2

要正确加入表格，您需要在它们之间找到一些共同点。基本语法是

SELECT fields from Table1 aliasname 
JOIN Table2 aliasname ON
table1aliasname.commonfield = table2aliasname.commonfield
WHERE wherecriteria

在这种情况下：

select count(distinct users.email) 
from users,subscriptions 
where subscription_plan_id=81 
and users.is_paying_customer = 'Y';

将用户与描述联系起来的内容..我假设您有一个名为userID的字段尝试这样的事情：

select count(distinct users.email) 
from users u
JOIN subscriptions s on u.userid = s.userid
where subscription_plan_id=81 
and users.is_paying_customer = 'Y';

Answer 3

SELECT COUNT(*) 
FROM (
    SELECT DISTINCT users.id
    FROM users INNER JOIN Subscriptions ON users.id = Subscriptions.user_id
    WHERE (Subscriptions.subscription_plan_id = 81) AND (users.is_paying_customer = 'Y')
) AS DistinctUsers

如何在sql中运行连接查询？

3 个答案: