I have a table that looks like this:
stuff
id integer
content text
score double
children[] (an array of id's from this same table)
I'd like to run a query that selects all the children for a given id, and then right away gets the full row for all these children, sorted by score.
Any suggestions on the best way to do this? I've looked into WITH RECURSIVE but I'm not sure that's workable. Tried posting at postgresql SE with no luck.
The following query will find all rows corresponding to the children of the object with id 14:
SELECT *
FROM unnest((SELECT children FROM stuff WHERE id=14)) t(id)
JOIN stuff USING (id)
ORDER BY score;
This works by finding the children of 14 as array first, then we convert it into a table using the unnest function, and then we join with stuff to find all rows with the given ids.
The ANY construct in the join condition would be simplest:
SELECT c.*
FROM stuff p
JOIN stuff c ON id = ANY (p.children)
WHERE p.id = 14
ORDER BY c.score;
Doesn't matter for the query whether the array of children IDs is in the same table or different one. You just need table aliases here to be unambiguous.
Related:
Similar solution:
With Postgres you can use a recursive common table expression:
with recursive rel_tree as (
select rel_id, rel_name, rel_parent, 1 as level, array[rel_id] as path_info
from relations
where rel_parent is null
union all
select c.rel_id, rpad(' ', p.level * 2) || c.rel_name, c.rel_parent, p.level + 1, p.path_info||c.rel_id
from relations c
join rel_tree p on c.rel_parent = p.rel_id
)
select rel_id, rel_name
from rel_tree
order by path_info;
Ref: Postgresql query for getting n-level parent-child relation stored in a single table
