Question

我正在尝试创建一个查询，在该查询中我选择了多个表以及每个表的一些数据，但是如果我创建count，它将失败。我希望有人能告诉我我在做什么错。

这是可以正常工作并带给我所有数据的人：

    SELECT *
            FROM profiles p
                LEFT OUTER JOIN(
                                SELECT u.id
                                    , u.nickname
                                    , u.email
                                    , w.idUserWished
                                    , l.idUserLiked
                                    , b.idBlocked
                                    , m.idMatched
                                    , m.accepted
                                        FROM users u
                                            LEFT OUTER JOIN wish w ON w.idUserWished = u.id
                                            LEFT OUTER JOIN likes l ON l.idUserLiked = u.id
                                            LEFT OUTER JOIN blocked b ON b.idBlocked = u.id
                                            LEFT OUTER JOIN matches m ON m.idMatched = u.id
                                        WHERE NOT EXISTS (
                                                            SELECT idBlock
                                                                FROM blocked b
                                                                WHERE b.idBlock = u.id AND b.idBlocked = 1) 
                                            AND u.id <> 1 
                                            ORDER BY id DESC LIMIT 0,5) AS p2 
                ON p.idUser = p2.id
                    WHERE p.gender = 'Femenino'
                        AND p.age BETWEEN 18 AND 24
                        AND p.alcohol = 'A diario'
                        AND p.smoke = 'A diario'
                        AND p.antro = 'A diario'
                        AND p.edoCivil = 'Casado'
                        AND p.height = 100
                        AND p.weight = 'Delgado'
                        AND p.skin = 'Clara'
                        AND p.location = 'Mexico'
                        AND p.state = 'Coahuila'

但是，如果我包含count，它将失败，仅带给我1条记录

    SELECT *
            FROM profiles p
                LEFT OUTER JOIN(
                                SELECT u.id
                                    , u.nickname
                                    , u.email
                                    , w.idUserWished
                                    , l.idUserLiked
                                    , b.idBlocked
                                    , m.idMatched
                                    , m.accepted
                                    , COUNT(DISTINCT msn.UserReceiver) AS 'cantidad'
                                        FROM users u 
                                            LEFT OUTER JOIN wish w ON w.idUserWished = u.id
                                            LEFT OUTER JOIN likes l ON l.idUserLiked = u.id
                                            LEFT OUTER JOIN blocked b ON b.idBlocked = u.id
                                            LEFT OUTER JOIN matches m ON m.idMatched = u.id
                                            LEFT OUTER JOIN messages msn ON msn.userEmitter = 1
                                        WHERE NOT EXISTS (
                                                            SELECT idBlock
                                                                FROM blocked b
                                                                WHERE b.idBlock = u.id AND b.idBlocked = 1) 
                                            AND u.id <> 1 ORDER BY id DESC LIMIT 0,5) AS p2 
                ON p.idUser = p2.id
                    WHERE p.gender = 'Femenino'
                        AND p.age BETWEEN 18 AND 24
                        AND p.alcohol = 'A diario'
                        AND p.smoke = 'A diario'
                        AND p.antro = 'A diario'
                        AND p.edoCivil = 'Casado'
                        AND p.height = 100
                        AND p.weight = 'Delgado'
                        AND p.skin = 'Clara'
                        AND p.location = 'Mexico'
                        AND p.state = 'Coahuila'

下一个查询示例

哪个作品

哪个不起作用

如果您能看到区别...当我设置计数时，只需给我带来1个昵称和1个电子邮件...但我希望给我带来所有数据

Answer 1

这里的问题是您使用的是count，而没有group by子句。在另一个数据库引擎中，它会导致语法错误，但在mysql中，它仍然可以接受并正常工作。但是，让我们看看mysql是如何通过小测试来工作的

    SELECT *, COUNT(*) AS 'cantidad' FROM users

此查询仅返回一个记录，即使表用户有很多记录。记录返回是表用户中第一条记录的总和，并对所有用户计数。

因此，不要在没有count的情况下使用group by，这会使查询不清楚。即使mysql仍然可以使用它，也很难弄清楚我的sql如何执行查询

要解决您的问题，因为您没有提供示例数据并无法预期结果，因此我不确定如何确切地解决您的问题。但是根据您的查询逻辑，我建议您更改

    , COUNT(DISTINCT msn.UserReceiver) AS 'cantidad'
    ....
    LEFT OUTER JOIN messages msn ON msn.userEmitter = 1

通过子查询

    ,(select COUNT(DISTINCT msn.UserReceiver) from messages msn where msn.userEmitter = 1) AS 'cantidad'

所以您的查询会这样

    SELECT *
            FROM profiles p
                LEFT OUTER JOIN(
                                SELECT u.id
                                    , u.nickname
                                    , u.email
                                    , w.idUserWished
                                    , l.idUserLiked
                                    , b.idBlocked
                                    , m.idMatched
                                    , m.accepted
                                    ,(select COUNT(DISTINCT msn.UserReceiver) from messages msn where msn.userEmitter = 1) AS 'cantidad'
                                        FROM users u 
                                            LEFT OUTER JOIN wish w ON w.idUserWished = u.id
                                            LEFT OUTER JOIN likes l ON l.idUserLiked = u.id
                                            LEFT OUTER JOIN blocked b ON b.idBlocked = u.id
                                            LEFT OUTER JOIN matches m ON m.idMatched = u.id
                                        WHERE NOT EXISTS (
                                                            SELECT idBlock
                                                                FROM blocked b
                                                                WHERE b.idBlock = u.id AND b.idBlocked = 1) 
                                            AND u.id <> 1 
                                            ORDER BY id DESC LIMIT 0,5) AS p2 
                ON p.idUser = p2.id
                    WHERE p.gender = 'Femenino'
                        AND p.age BETWEEN 18 AND 24
                        AND p.alcohol = 'A diario'
                        AND p.smoke = 'A diario'
                        AND p.antro = 'A diario'
                        AND p.edoCivil = 'Casado'
                        AND p.height = 100
                        AND p.weight = 'Delgado'
                        AND p.skin = 'Clara'
                        AND p.location = 'Mexico'
                        AND p.state = 'Coahuila'

查询MySQL的麻烦

1 个答案: