Question

我有两个表：users和user_meta。我想在与常规用户信息相同的查询中获取所有用户的元行。如何加入user_meta表的行，这些行在第一个表中可以作为列使用呢？

user_meta：user_id（int 15），context（varchar 250），value（varchar 250）

       SELECT 
             m.user_id AS id, m.member_group_id, m.avatar_id, m.display_name, m.email_address, UNIX_TIMESTAMP(m.join_date) AS join_date, m.status,
             l.member_id, COUNT(l.member_id) AS total_listings,
             g.group_id, g.title AS group_title,
             a.attachment_id, a.file_path AS avatar_path
        FROM users AS m
        LEFT JOIN user_meta AS meta ON m.user_id = meta.user_id
        LEFT JOIN listings AS l ON l.member_id = m.user_id
        LEFT JOIN groups AS g ON m.member_group_id = g.group_id
        LEFT JOIN attachments AS a ON m.avatar_id = a.attachment_id
        WHERE m.user_id = ".$id."
        GROUP BY m.user_id
        LIMIT 1

Answer 1

只需尝试此m.user_id AS id ORDER BY ASC

即可

Answer 2

请澄清你的问题。你提到2个表：用户＆amp;元数据，但在查询示例中，您有表列表，组和附件。您要对哪个元数据字段进行排序？

请记住，要使count（l.member_id）正常工作，您必须将所有其他字段分组：

Group by  m.user_id , m.member_group_id, m.avatar_id, m.display_name, m.email_address, UNIX_TIMESTAMP(m.join_date), m.status,
             l.member_id,  g.group_id, g.title ,
             a.attachment_id, a.file_path

如果您不想按所有其他字段进行分组，则必须创建一个子查询，如下例所示，其中子查询用于计数。

SELECT 
             m.user_id AS id, m.member_group_id, m.avatar_id, m.display_name, m.email_address, UNIX_TIMESTAMP(m.join_date) AS join_date, m.status,
             l.member_id, 

(select COUNT(l.member_id) from listings where listings.member_id=m.user_id)  AS total_listings,

             g.group_id, g.title AS group_title,
             a.attachment_id, a.file_path AS avatar_path
        FROM users AS m
        LEFT JOIN user_meta AS meta ON m.user_id = meta.user_id
        LEFT JOIN listings AS l ON l.member_id = m.user_id
        LEFT JOIN groups AS g ON m.member_group_id = g.group_id
        LEFT JOIN attachments AS a ON m.avatar_id = a.attachment_id
        WHERE m.user_id = ".$id."
order by         
m.user_id
        LIMIT 1

mysql将另一个表的行连接为查询中的列

2 个答案: