Database

Find student who saved the evaluation but not submit yet

SELECT * FROM users 
WHERE id IN 
    (SELECT distinct(evaluator) FROM evaluation_mixevals WHERE event_id = EVENTID AND evaluator NOT IN 
        (SELECT distinct(submitter_id) FROM evaluation_submissions WHERE event_id = EVENTID)
    );

Replace EVENTID to event id.

Submit for those students

INSERT INTO evaluation_submissions 
    SELECT NULL,EVENTID, group_events.id, user_id,1,NOW(),'A',1,NOW(),NULL,NOW() 
    FROM groups 
    LEFT JOIN groups_members ON groups.id = groups_members.group_id 
    LEFT JOIN group_events ON group_events.group_id = groups.id 
    WHERE course_id = COURSEID AND user_id IN 
          SELECT id FROM users 
          WHERE id IN 
          (SELECT distinct(evaluator) FROM evaluation_mixevals WHERE event_id = EVENTID AND evaluator NOT IN 
              (SELECT distinct(submitter_id) FROM evaluation_submissions WHERE event_id = EVENTID)
          );;

Replace EVENTID to event id and COURSEID to course id.