与外部表的MySQL嵌套集层次结构

Question

我在MySQL表中使用嵌套集来描述类别的层次结构，以及描述产品的附加表。

分类表;

id 
name 
left 
right 

产品表;

id 
categoryId 
name 

如何检索产品的完整路径（包含所有父类别）？即：

RootCategory > SubCategory 1 > SubCategory 2 > ... > SubCategory n > Product

例如说我想列出从SubCategory1所有产品和它的子类，并与每个给定Product我要完整的树路径，该产品 - 这可能吗？

这是据我已经得到了 - 但结构不太对劲......

select 
parent.`name` as name, 
parent.`id` as id, 
group_concat(parent.`name` separator '/') as path 
from 
categories as node, 
categories as parent, 
(select 
    inode.`id` as id, 
    inode.`name` as name 
from 
    categories as inode, 
    categories as iparent 
where 
    inode.`lft` between iparent.`lft` and iparent.`rgt` 
    and 
    iparent.`id`=4 /* The category from which to list products */ 
order by 
    inode.`lft`) as sub 
where 
node.`lft` between parent.`lft` and parent.`rgt` 
and 
node.`id`=sub.`id` 
group by 
sub.`id` 
order by 
node.`lft` 

Answer 1

嘿，我想我解决了它！ ：D

select 
    sub.`name` as product, 
    group_concat(parent.`name` separator ' > ') as name 
from 
    categories as parent, 
    categories as node, 
    (select 
     p.`name` as name, 
     p.`categoryId` as category 
    from 
     categories as node, 
     categories as parent, 
     products as p 
    where 
     parent.`id`=4 /* The category from which to list products */ 
     and 
     node.`lft` between parent.`lft` and parent.`rgt` 
     and 
     p.`categoryId`=node.`id`) as sub 
where 
    node.`lft` between parent.`lft` and parent.`rgt` 
    and 
    node.`id`=sub.`category` 
group by 
    sub.`category` 

Answer 2

要提取父母节点上，您只需要......最后left/right值（子类别n）节点。

1. 取您的产品：SELECT ... FROM product p JOIN category c ON c.id = p.category_id WHERE p.id = ?。
2. 取父母：SELECT ... FROM category WHERE leftCol <= {productCategory['left']} AND rightCol >= {productCategory['right']}

这就是你需要相当一切。