php - 如何按值对 SQL 行进行排序？

Question

如何选择 user_ids B meta_key 和order by ratings meta_value？

    user_id    |    meta_key    |    meta_value-----------------------------------------------------       1                A                1       1                B                1       1                C                1       1              rating             9       8                A                1       8                C                1       8              rating           99999       7                A                1       7                B                1       7                C                1       7              rating            999

我需要获取具有 B meta_key 的用户的 ID，然后按用户评分 值对 ID 进行排序。

Answer 1

试试这个:

SELECT T1.user_id
    FROM yourtable T1 
    JOIN yourtable T2
        ON T1.user_id = T2.user_id
        AND T2.meta_key = 'rating'
    WHERE T1.meta_key = 'B'
    ORDER BY CAST(T2.meta_value AS SIGNED)