mysql从同一表中选择类别e子类别

问题描述

我有下表称为“产品”：

id INT 11
product_name VARCHAR 255
category VARCHAR 255
subcategory VARCHAR 255
subsubcategory VARCHAR 255

我想在一个查询中读取所有类别，子类别和子子类别（每个类别一次）。

目前，我有以下查询，但是我不确定它是否有效：

SELECT category,subcategory,subsubcategory FROM products WHERE category != '' GROUP by category,subsubcategory ORDER by category ASC,subcategory ASC,subsubcategory ASC

输出应类似于：

clothes (main category)
clothes > pants (sub category)
clothes > pants > man (sub sub category)
clothes > pants > woman
clothes > skirt
jewelry
jewelry > necklace

解决方法

您可以这样做：

select category as rendered from products
union all 
select concat(category,' > ',subcategory) from products
union all 
select concat(category,subcategory,subsubcategory) from products
order by rendered