Select average from join MYSQL - mysql

Question

I am trying to get an average on the last join:
INNER JOIN rating r
ON r.rid = (SELECT MAX(rid) FROM rating WHERE uid = u.uid ORDER BY rid DESC LIMIT 1)
I am having some problems getting it to give me a rating with 1 decimal like 4.3 in rating. How can i do this in a simple way?
SELECT p.uid, u.name, u.description, u.url, u.picurl, u.mapurl, p.pid, p.price, r.rid, r.rating FROM utested u
INNER JOIN price p
ON p.pid = (SELECT MAX(pid) FROM price WHERE uid = u.uid ORDER BY uid DESC LIMIT 1)
INNER JOIN rating r
ON r.rid = (SELECT MAX(rid) FROM rating WHERE uid = u.uid ORDER BY rid DESC LIMIT 1)
ORDER BY u.name;
I have created a sql fiddle so you can try out the queries.
http://sqlfiddle.com/#!2/93b771/1

Answer 1

Consider the following. How does this result differ from the desired result?
+-----+------------+-------------+----------+------------+--------------+-----+-------+-----+--------+
| uid | name | description | url | picurl | mapurl | pid | price | rid | rating |
+-----+------------+-------------+----------+------------+--------------+-----+-------+-----+--------+
| 5 | Havana Pub | | | | | 35 | 74 | 11 | 5 |
| 3 | Hos Naboen | | | | | 33 | 74 | 9 | 5 |
| 2 | Javel | Musikk | javel.no | pic.jave.. | map.javel.no | 38 | 88 | 8 | 5 |
| 1 | Kick | Yay | kick.no | http://p.. | map.kick.no | 31 | 74 | 15 | 1 |
| 6 | Leopold | | | | | 36 | 74 | 12 | 5 |
| 4 | Victoria | | | | | 37 | 75 | 10 | 5 |
+-----+------------+-------------+----------+------------+--------------+-----+-------+-----+--------+
OK. I'm going to take a wild stab in the dark here...
SELECT p.uid
, u.name
, u.description
, u.url
, u.picurl
, u.mapurl
, p.pid
, p.price
, AVG(r.rating) rating
FROM utested u
JOIN price p
ON p.uid = u.uid
JOIN ( SELECT uid, MAX(pid) latest_price FROM price GROUP BY uid ) px
ON px.uid = p.uid
AND px.latest_price = p.pid
JOIN rating r
ON r.uid = u.uid
GROUP
BY u.name;
+-----+------------+-------------+----------+--------------+--------------+-----+-------+--------+
| uid | name | description | url | picurl | mapurl | pid | price | rating |
+-----+------------+-------------+----------+--------------+--------------+-----+-------+--------+
| 5 | Havana Pub | | | | | 35 | 74 | 5.5000 |
| 3 | Hos Naboen | | | | | 33 | 74 | 4.0000 |
| 2 | Javel | Musikk | javel.no | pic.javel... | map.javel.no | 38 | 88 | 5.0000 |
| 1 | Kick | Yay | kick.no | http://pri.. | map.kick.no | 31 | 74 | 3.4000 |
| 6 | Leopold | | | | | 36 | 74 | 3.5000 |
| 4 | Victoria | | | | | 37 | 75 | 4.0000 |
+-----+------------+-------------+----------+--------------+--------------+-----+-------+--------+