Maybe the following will work, where YYY is the phase that you are looking for.
SELECT u.firstname, u.lastname, fv.value
FROM mdl_feedback_value fv
JOIN mdl_user u ON u.id = fv.id
WHERE value LIKE "%YYY%"
SELECT u.firstname, u.lastname, fv.value
FROM mdl_feedback_value fv
JOIN mdl_user u ON u.id = fv.id
WHERE value LIKE "%YYY%"