mysql查询提供数据但跳过空值

Question

我有以下查询，它给出了结果但不是预期的结果

select g.id
     , g.name
     , COUNT(p1.id) as total 
  from ft_smsender_groups as g
     , ft_smsender_persons as p1
     ,ft_smsender_persons2groups as p2 
 where g.id = p2.group_id 
   and p1.id = p2.person_id 
 group 
    by id
     , name

这给了我与每个人相关联的群体的值(value)，

但它会跳过那些没有任何人关联的组，

我需要修改此查询以提供所有组名，因此我没有分配任何人，它应该将 total 列值指定为 0

Answer 1

这样试试

select g.id,g.name, count(p2.id) as total from ft_smsender_
groups as g left join (select p1.id,p2.group_id 
from ft_smsender_persons2groups as p2  inner join ft_smsender_persons 
as p1 on p1.id = p2.person_id ) as p2 on g.id = p2.group_id group by id,name