使用Codeigniter和MySQL从同一个表中获取对等列值

Question

How can I get peer column values if parent id matches. In the below example, I'll give subcat_id as 42 and based on cat_id(6) it should give me 41 and 43.

cat_id----subcat_id---name
===========================
5---------40----------ABC
6---------41----------DEF
6---------42----------GHI
6---------43----------JKL

Thanks.

Answer 1

Is this what you are looking at. Also I would suggest to have a primary key in the table.

select 
t2.cat_id ,
t2.subcat_id,
t2.name
from test t1
join test t2 on t1.cat_id = t2.cat_id
where t1.subcat_id = 42 AND t2.subcat_id <> 42

DEMO

Also checkout http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/