Question

我正在尝试从所有东西中选择所有内容，并计算更多资料中的东西id = morestuff id。

select *,
    COUNT(morestuff.items) as total
from stuff,
    morestuff
where stuff.id = '{$id}'
    and morestuff.id = stuff.id

显然我的查询有问题，有人可以帮忙吗？

Answer 1

SELECT s.*, coalesce(ms.Count, 0) as Count
FROM stuff s
left outer join (
    select id, count(*) as Count
    from morestuff
    group by id
) ms on s.id = ms.id
WHERE s.id='{$id}'

Answer 2

这可能是另一种选择：

select
  *, (
    select count(*)
    from morestuff
    where morestuff.id = stuff.id
      ) as total
from stuff
where id = '{$id}'

SQL同时选择和计数

2 个答案: