MYSQL:每个组的最大n问题

Question

greatest-n-per-group的问题，我的MySQL版本不能使用LIMIT & IN (错误1235)，所以我需要使用这种查询(请看这里的答案：answer )

SELECT
                t1.idMemberCard,
                DATE(MIN(transactions.dateTransaction)) AS first_transaction,
                DATE(MAX(transactions.dateTransaction)) AS last_transaction,
                t2.*
                FROM membersCard AS t1
                INNER JOIN transactions ON transactions.idMemberCard = t1.idMemberCard
                INNER JOIN
                (
                    SELECT
                        membersCard.idMemberCard,
                        membersCard.cardNumber,
                        membersCard.firstNameMemberCard,
                        membersCard.lastNameMemberCard,
                        transactions.dateTransaction
                    FROM membersCard
                    INNER JOIN transactions ON transactions.idMemberCard = membersCard.idMemberCard
                    WHERE membersCard.sexMemberCard = 'M'
                    AND membersCard.cardNumber = '1100101308655'
                    AND
                    DATE(transactions.dateTransaction) BETWEEN ('2013-12-28') AND ('2014-08-13')
                    LIMIT 100
                ) AS t2
                ON t1.idMemberCard = t2.idMemberCard

为精确匹配(卡号)而执行的子查询(t2表)恰好返回5行(在本例中)：全部完美。

我的问题/请求：

将这两个表连接起来，我将获得5行，而不只是1行，不同的5行包含日期。

Answer 1

您的join工作正常。问题出在你的select语句上：

 SELECT t1.idMemberCard,
        DATE(MIN(transactions.dateTransaction)) AS first_transaction,
        DATE(MAX(transactions.dateTransaction)) AS last_transaction,
        t2.*

使用MIN()和MAX()将其转换为只返回一行的聚合查询。试试这个：

 SELECT t1.idMemberCard,
        DATE(transactions.dateTransaction) AS first_transaction,
        DATE(transactions.dateTransaction) AS last_transaction,
        t2.*

如果需要，也可以添加group by子句。