I have a simple MySQL table thats contains a list of categories, level is determined by parent_id:
id name parent_id
---------------------------
1 Home 0
2 About 1
3 Contact 1
4 Legal 2
5 Privacy 4
6 Products 1
7 Support 1
I'm attempting to make a breadcrumb trail. So i have the 'id' of the child, I want to get all available parents (iterating up the chain until we reach 0 "Home"). There could be any number or child rows going to an unlimited depth.
Currently I am using an SQL call for each parent, this is messy. Is there a way in SQL to do this all on one query?
Adapted from here:
SELECT T2.id, T2.name
FROM (
SELECT
@r AS _id,
(SELECT @r := parent_id FROM table1 WHERE id = _id) AS parent_id,
@l := @l + 1 AS lvl
FROM
(SELECT @r := 5, @l := 0) vars,
table1 h
WHERE @r <> 0) T1
JOIN table1 T2
ON T1._id = T2.id
ORDER BY T1.lvl DESC
The line @r := 5
is the page number for the current page. The result is as follows:
1, 'Home'
2, 'About'
4, 'Legal'
5, 'Privacy'