带有count和left join的SQL查询

Question

我有一个查询，我需要从2个表中计算'userID'。

SQL QUERY：

    SELECT DISTINCT TOP 1000 u.id as userID, u.firstName as userFirstName, u.email as userEmail, u.phone as userPhone, 
count(ueo.userID) as opensEmailCounter, count(ush.userID) as opensSmsCounter
    FROM dbo.Users u
    LEFT JOIN dbo.UserEmailsOpens ueo ON u.id = ueo.userID AND ueo.targetID = 4
    LEFT JOIN dbo.UserSmsHistory ush ON u.id = ush.userID AND ush.targetID = 4 AND ush.opened = 1
    WHERE u.deleted = 0
    AND IsNull(u.firstName, '') != '' 
    AND IsNull(u.email, '') != '' 
    AND IsNull(u.phone, '') != ''
GROUP BY u.id, u.firstName, u.email, u.phone

但是，结果并不是我的预期。在我做了第二次左连接后，它给了我错误的数字。在某些情况下，它是我的结果的两倍，并显示相同的计数结果（附上截图）。

Answer 1

在加入之前聚合如下：

{{1}}

Answer 2

稍微修改了你的查询。使用Case When来消除结果中空白的计数。

Select userID, userFirstName, userEmail, userPhone, 
sum(case when ueo_userID <> '' then 1 else 0 end) as opensEmailCounter,
sum(case when ush_userID <> '' then 1 else 0 end) as opensSmsCounter
from
 (
    SELECT DISTINCT u.id as userID, u.firstName as userFirstName, u.email as userEmail, u.phone as userPhone, 
    ueo.userID as ueo_userID, ush.userID as ush_userID
    FROM dbo.Users u
    LEFT JOIN dbo.UserEmailsOpens ueo ON u.id = ueo.userID AND ueo.targetID = 4
    LEFT JOIN dbo.UserSmsHistory ush ON u.id = ush.userID AND ush.targetID = 4 AND ush.opened = 1
    WHERE u.deleted = 0user
    AND IsNull(u.firstName, '') != '' 
    AND IsNull(u.email, '') != '' 
    AND IsNull(u.phone, '') != ''
 ) a
GROUP BY userID, userFirstName, userEmail, userPhone;

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