php - 如何按值对 SQL 行进行排序？

Question

如何按Bmeta_key选择user_ids和按评分排序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

我需要获取拥有 B meta_key 的用户 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)