Question

I have a table with the following structure –

Category {Id, Name, ParentId}

I have values like this –

id  name               parentid
-------------------------------
1   Technology Focus   NULL
2   Tools              1
3   Database           1

How do I write a query that displays like this –

name (parent)      name (child)             
--------------------------------
Technology Focus   Tools
Technology Focus   Database
etc..

I believe I need to use the Group By clause but I’m not quite getting it.

Answer 1

if i’m looking at that correctly, i think you just need

select parent.name, child.name 
from category child
  inner join category parent
    on parent.id = child.parentid