MySQL查询和从其他表计数

Question

我想从一个表中获取数据，并根据第一个表数据计算来自其他表的所有结果，这是我尝试的：

SELECT
    cars.*, (
        SELECT
            COUNT(*)
        FROM
            uploads
        WHERE
            uploads.cid = cars.customer
    ) AS `count`,
FROM
    `cars`
WHERE
    customer = 11;

我真的不知道为什么它不起作用，因为我不是一个普通的MySQL用户/编码器......

任何人都可以指导我这个方向吗？

Answer 1

使用LEFT JOIN连接两个表来尝试它

SELECT  a.customer, COUNT(b.cid) totalCount
FROM    cars a
        LEFT JOIN uploads b
            ON a.customer = b.cid
WHERE   a.customer = 11
GROUP BY a.customer

在LEFT JOIN使用COUNT(*)将使记录的最小计数为1。

Answer 2

SELECT
    c.*, COUNT(u.cid) AS count
FROM
    cars c
LEFT JOIN 
    uploads u
ON
    u.cid=c.customer
WHERE
    u.customer = 11;
GROUP BY c.cid

Answer 3

SELECT  cars.*,COUNT(uploads.*) as uplloaded 
from cars 
left outer join uploads on  uploads.cid = cars.customer
where  cars.customer = 11 
group by uploads.cid;

Answer 4

尝试这个 ：

SELECT  customer, COUNT(cid) totalCount
FROM    cars 
        INNER JOIN uploads 
            ON (customer = cid)
WHERE   customer = 11
GROUP BY customer