Php 无法选择带有案例条件的计数

我有两张桌子：

用户组

用户\组\有\个用户

我想统计每个组的用户数，并得出类似的结果：

id    name    user_count
2     gn2     2
1     gn1     0

我试过这个问题

select g.*,
       count(cg.user_id) as user_count
from user_groups as g
left join user_group_has_users as cg on cg.user_group_id = g.id
where g.created_user = 3

SELECT g.* ,COUNT(cg.user_id) AS user_count 
FROM user_groups g 
LEFT JOIN user_group_has_users cg ON cg.group_id = g.id 
WHERE  g.created_user = 3 
GROUP BY g.id 
ORDER BY user_count DESC ;

但它只返回一行。我不明白为什么会这样。

---

请在这方面帮助我。

左连接，其中条件是内部连接。你可能想要

select 
ug.id,
ug.name,
count(ughu.user_id) as user_count 
from user_groups ug 
left join user_groups_has_users ughu on ughu.group_id = ug.id 
and ug.created_user = 3 
group by ug.id
order by user_count desc ;

如果仍要使用创建的

用户=3

筛选数据，请使用内部联接，并将条件移动到

where子句

使用此查询

select g.*,
       count(cg.user_id) as user_count
from user_groups as g
left join user_group_has_users as cg on cg.user_group_id = g.id
where g.created_user = 3

SELECT g.* ,COUNT(cg.user_id) AS user_count 
FROM user_groups g 
LEFT JOIN user_group_has_users cg ON cg.group_id = g.id 
WHERE  g.created_user = 3 
GROUP BY g.id 
ORDER BY user_count DESC ;

---

小心骨料和接头。在某些情况下，数字被夸大了

看看这是否适合您：

select  g.*, 
      ( SELECT  count(*)
            FROM  user_group_has_users
            WHERE  user_group_id = g.id 
      ) AS user_count
    from  user_groups as g
    where  g.created_user = 3

---

我不明白那个输出在算什么。它在算属于该组的用户总数。试试这个，在你的查询组之后添加cg.user\U group\U IDThank@ZinalShah它对我有用。