Analytics and reporting

Hi i try get feedback by each user with mysql query, but all time i get or Empty or Null, here my mySQL:

SELECT DISTINCT
  u.id AS userid,
  gs.heading AS heading,
  gi.itemname AS itemname,
  ROUND( g.finalgrade) AS finalgrade,
  f.feedbacktext AS feedbacktext
  FROM mdl_user u
  JOIN mdl_grade_grades g ON g.userid = u.id
  JOIN mdl_grade_items gi ON g.itemid =  gi.id
  JOIN mdl_course c ON c.id = gi.courseid
  JOIN mdl_quiz_sections gs ON gs.id = u.id
  JOIN mdl_quiz_feedback f ON f.id = 149
 
  WHERE u.id = 12 AND finalgrade AND itemname is not null


i can added for this   JOIN mdl_quiz_feedback f ON f.id = 149 - where 149 this ID for feedback, but this wrong solution, how i can do this?
Thank you