Question

How can I know/ check a requested page/ row is a sub row or sub-sub row?

For instance, this is my page table,

pg_id   pg_url  pg_title    parent_id
1       a       a           1
2       b       b           2
3       aa      aa          1
4       aaa     aaa         3

pg_id 3 is a sub page as its parent is pg_id 1, while pg_id 4 is a sub-sub page as its parent is pg_id 3

Here is my query how I get the info usually,

SELECT 
p.pg_id, 
p.pg_url,
p.parent_id

FROM root_pages AS p
WHERE p.pg_id = '4'

but it does not give info whether this requested is a sub or sub-sub page.

is any way to achieve this with a query?

Answer 1

I think you would want something like this:

SELECT 
p.pg_id, 
p.pg_url,
p.parent_id,
p2.pg_id as 'ParentPageID',
p3.pg_id as 'GrandparentPageID'

FROM root_pages AS p
LEFT JOIN root_pages AS p2 on p.parent_id = p2.pg_id AND p.pg_id <> p2.pg_id
LEFT JOIN root_pages AS p3 on p2.parent_id = p3.pg_id AND p2.pg_id <> p3.pg_id
WHERE p.pg_id = '4'

If the grandparent page ID isn’t null, it’s a sub-sub page. If it is, but the parent page ID isn’t null, it’s a sub-page.