Question

我有3个表，想要进行sql查询以正确查看它们。

1。）Zakaz

id | Comment

2。）Tovar

id  | id_clients | zakaz

3.）用户

id | name

它们连接为：

zakaz.id = tovar.zakaz
tovar.id_clients = users.id

我想看看

zakaz.id | users.name

但是我想每个zakaz只限制1个字符串，所以我做了：

SELECT zakaz.id, zakaz.comment, tovar.id_clients
    FROM zakaz
    JOIN tovar ON zakaz.id = tovar.zakaz
GROUP BY zakaz.id

然后我想加入用户，但它不起作用

SELECT zakaz.id, zakaz.comment, tovar.id_clients, users.name
    FROM zakaz
    JOIN tovar ON zakaz.id = tovar.zakaz
    GROUP BY zakaz.id
JOIN users ON users.id = tovar.id_clients

Answer 1

它会在Zakaz

上显示最新的ID

SELECT  a.name, c.id
FROM    Users a
            INNER JOIN
            (
                SELECT id_clients, zakaz, MAX(id) maxID
                FROM Tovar
                GROUP BY id_clients, zakaz
            ) d 
                ON d.id_clients = a.id
            INNER JOIN Zakaz c
                ON d.zakaz = c.id

2加入MYSQL和LIMIT 1

1 个答案: