SELECT s.name AS name, sv.value AS value, s.category AS category,s.id AS sid
FROM usr_skills usk
LEFT JOIN (SELECT value, skill_id, usr_id FROM skill_valuations ORDER BY last_change DESC LIMIT 1) sv ON sv.skill_id = usk.skill_id
LEFT JOIN skills s ON usk.skill_id = s.id
WHERE usk.usr_id = 1

PHP - NULL - Technology 10
MySQL - NULL - Databases - 11
Python - NULL - Technology - 12

PHP - 5.26 - Technology 10
MySQL - NULL - Databases - 11
Python - NULL - Technology - 12

PHP - 5.26 - Technology 10
PHP - 5.59 - Technology 10
MySQL - NULL - Databases - 11
Python - NULL - Technology - 12