mySQL hierarchical grouping sort

Question

I have a schema that essentially looks like this:

CREATE TABLE `data` (
  `id` int(10) unsigned NOT NULL,
  `title` text,
  `type` tinyint(4),
  `parent` int         


        

Answer 1

You said you wanted it to sort on the titles, correct?

SELECT id, title, parent
FROM
  ( SELECT id, title, parent,
    CASE WHEN parent is null THEN title ELSE CONCAT((SELECT title FROM `data` d2 WHERE d2.id = d.parent), '.', d.title) END AS sortkey
    FROM `data` d
   ) subtable
ORDER BY sortkey

edit: Edited to remove type from the query.

Answer 2

SELECT * FROM `data` ORDER BY COALESCE(`parent`, `id`), `parent`, `id`

Answer 3

Here's a solution tested to work on SQL Server. Should be essentially the same on MySQL

select Id, Title, [Type], Id as OrderId from Hier h1 where [Type] = 1
union
select Id, Title, [Type], Parent as OrderId from Hier h2 where [Type] = 2
order by OrderId, [Type]