ERROR: column "ur.rating" must appear in the GROUP BY clause or be used in an aggregate function

LINE 3: ... ur.id, ur.userid, ur.scaleid, ur.rating ...

^

SELECT r.itemid, r.component, r.ratingarea, r.contextid,

AVG(r.rating) AS aggrrating, COUNT(r.rating) AS numratings,

ur.id, ur.userid, ur.scaleid, ur.rating AS usersrating

FROM mdl_rating r

LEFT JOIN mdl_rating ur ON ur.contextid = r.contextid AND

ur.itemid = r.itemid AND

ur.component = r.component AND

ur.ratingarea = r.ratingarea AND

ur.userid = $1

WHERE r.contextid = $2 AND

r.itemid = $3 AND

r.component = $4 AND

r.ratingarea = $5

GROUP BY r.itemid, r.component, r.ratingarea, r.contextid, ur.id, ur.userid, ur.scaleid

ORDER BY r.itemid

[array (

0 => '2',

1 => '28',

2 => '31',

3 => 'mod_forum',

4 => 'post',

)]