Joining Multiple MySQL Statements - mysql

Question

I have multiple queries I perform that I would like to join together.
The first query converts a user supplied path into an id. Paths can have multiple ids associated with them so I want to ensure I get the most recently created id for the path:
SELECT id FROM paths WHERE path=$path ORDER BY created DESC LIMIT 1
Once I know the id number I can perform the rest of my queries.
I have the most recently created id for the path but I need to also verify I have the most recently created path for that id (sometimes they are not the same):
SELECT path FROM paths WHERE id={id} ORDER BY created DESC LIMIT 1
I'd like to include the id's rating and the count of votes though sometimes there are none:
SELECT AVG(vote) AS rating, COUNT(*) AS count FROM votes WHERE id={id} GROUP BY id
Finally I'd like to include everything from a third table about the id (the id is UNIQUE on this table so there cannot be multiple lines):
SELECT * FROM places WHERE id={id}
How can I best join these statements together?

Answer 1

You can join them together into one query like this:
select pl.*, avg(vote) as rating
from (SELECT path, id
FROM paths
WHERE path = {path}
ORDER BY created DESC
LIMIT 1
) p left outer join
votes v
on v.id = p.id left outer join
places pl
on pl.id = p.id
group by p.id;
EDIT:
The first two conditions do seem redundant. But, if you need them:
select pl.*, avg(vote) as rating
from (SELECT path, id
FROM paths
WHERE id = (select id from paths where path = {path} order by created desc limit 1)
ORDER BY created DESC
LIMIT 1
) p left outer join
votes v
on v.id = p.id left outer join
places pl
on pl.id = p.id
group by p.id;