左连接相同的表两次，但一列重复

Question

主表希望两次使用同一列的reffrence表连接两次。 主表列是带整数的insert，需要与refference表连接以使字符返回以便为用户显示。 下面的sql没有显示任何记录，为什么？

主要表BD_BRAND

Sports_BR  Leather_BR
   2          1

参考表BD_REF

ID   NME         REF_TYPE
1    NIKE      Sports_Brand
2    ADIDAS    Sports_Brand
3    PUMA      Sports_Brand
1    CLACKS    Leather_Brand
2    LOTTUSSE  Leather_Brand
3    CHEANEY   Leather_Brand





   SELECT B.NME AS Sports_BR, C.NME AS Leather_BR  
    FROM BD_BRAND A
    LEFT JOIN BD_REF B on B.ID =  A.Sports_BR  
    LEFT JOIN BD_REF C on C.ID =  A.Leather_BR

我想要的结果如下：

Sports_BR  Leather_BR
 ADIDAS     CLACKS

Answer 1

我认为你在寻找：

SELECT B.NME AS Sports_BR, C.NME AS Leather_BR  
FROM BD_BRAND A
LEFT JOIN BD_REF B on B.ID =  A.Sports_BR and B.REF_TYPE = 'Sports_Brand' 
LEFT JOIN BD_REF C on C.ID =  A.Leather_BR and B.REF_TYPE = 'Leather_Brand' 

由于参考类型不同，您的ID会多次出现，因此您需要指定参考类型要抓取的ID。