mysql - 基于连接从多个表检索数据时出错

Question

I have following query which is not working it gives following error

1054 - “on 子句”中的未知列“league_members.l_id”

SQL查询

SELECT bhk.u_manager, leaderboard.total_pts 
from bhk LEFT JOIN leaderboard on bhk.u_id=leaderboard.u_id and league_members.l_id=1;  

Answer 1

这里您需要一个双SQL JOIN，以及一个条件。

由于您使用三个表:

• bhk;
• 排行榜；
• league_members。

您的查询应如下所示:

    SELECT bhk.u_manager, leaderboard.total_pts
    FROM bhk
    LEFT JOIN leaderboard ON bhk.u_id=leaderboard.u_id
    LEFT JOIN league_members ON league_members.l_id = **LINK TO OTHER TABLE ID**
    WHERE league_members.l_id=1; 

希望对你有帮助。