mysql - 子查询返回多于 1 行

Question

尝试在查询中进行 2 次计数时出现此错误

首先我会向您展示查询:

$sql = mysql_query("select c.id, c.number, d.name, 
                    (select count(*) from `parts` where `id_container`=c.id group by `id_car`) as packcount,
                    (select count(*) from `parts` where `id_container`=c.id) as partcount
                    from `containers` as c
                    left join `destinations` as d on (d.id = c.id_destination)
                    order by c.number asc") or die(mysql_error());

现在 parts 表有 2 个我需要在计数中使用的字段:id_carid_container

id_car = 零件所属汽车的 IDid_container = 部件所在容器的 ID

对于 packcount 我想要的是每个容器的汽车总数对于 partcount 我想要的是每个容器的零件总数

Answer 1

这是因为您正在使用 GROUP BY

尝试类似的事情

(select count(distinct id_car) from `parts` where `id_container`=c.id)

在你的子查询中(现在无法检查)

编辑

PFY - 我认为 UNIQUE 用于索引