mysql - 选择类别列表有父类别名称吗？

Question

我的问题是如何让类别列表显示在具有父名称的表中？

类别表结构如下:

类别数据:

ID  vn_name   en_name   parent_id   path
-----------------------------------------------
1   Sanpham   Product   0            0-1-
2   Apple     Apple     1            0-1-2-
3   Sony      Sony      1            0-1-3-
4   Iphone    Iphone    2            0-1-2-4-
5   Ipad      Ipad      2            0-1-2-5-
6   Xperia    Xperia    3            0-1-3-6-
...

那么，如何查询来获取这样的列表？

ID  vn_name   en_name   vn_parent     en_parent      
-----------------------------------------------------
1   Sanpham   Product   Root            Root         
2   Apple     Apple     Sanpham         Product      
3   Sony      Sony      Sanpham         Product
4   Iphone    Iphone    Apple           Apple
5   Ipad      Ipad      Apple           Apple
6   Xperia    Xperia    Sony            Sony
...

Answer 1

您可以通过使用 LEFT JOIN 连接表本身来实现此目的。

试试这个:

select c1.id,
       c1.vn_name,
       c1.en_name,
        -- if parent id is 0 then make it root
       if(c1.parent_id =0,'root',c2.vn_name) as vn_parent,
       if(c1.parent_id =0,'root',c2.en_name) as en_name
from Category c1 left join Category c2 on c1.parent_id=c2.id
order by c1.id

SQL fiddle 示例: http://sqlfiddle.com/#!9/b6a63/3