Selecting records in order of parent id

Question

Simple question.. just can\'t get the result set in the order I need :p

I have a table \"categories\"

id    | name     | parent
1       apple      0
         


        

Answer 1

If those with no parents had null in their parent column, your statement would be very simple:

SELECT id, name, parent FROM categories order by coalesce(parent, id), id;

If you insist on 0 representing no parent, you can use more verbose CASE WHEN ... THEN ... statement.

Edit:

-- Sorting by name instead
select a.id, a.name, a.parent 
from categories a left join categories b on a.parent=b.id 
order by coalesce(b.name, a.name), a.name