explain select db1.questionnaire_question.content AS 'question content', 
db1.questionnaire_quest_choice.content AS 'choice content', 
avg(db1.questionnaire_response_rank.rank) AS 'average rank' 
from db1.questionnaire_response_rank 
INNER JOIN db1.questionnaire_question ON (db1.questionnaire_response_rank.question_id=db1.questionnaire_question.id) 
INNER JOIN db1.questionnaire_quest_choice ON (db1.questionnaire_quest_choice.question_id=db1.questionnaire_question.id) 
INNER JOIN db1.questionnaire ON (db1.questionnaire.id=db1.questionnaire_question.survey_id) 
INNER JOIN db1.local_ltiprovider ON (db1.questionnaire.course=db1.local_ltiprovider.courseid) 
INNER JOIN db1.local_ltiprovider_user ON (db1.local_ltiprovider_user.toolid=db1.local_ltiprovider.id) 
INNER JOIN db2.i_users_sections ON (db1.local_ltiprovider_user.sourceid=db2.i_users_sections.id) 
INNER JOIN db2.course_sections ON (db2.course_sections.id=db2.i_users_sections.course_section_id) 
INNER JOIN db2.courses ON (db2.courses.id=db2.course_sections.course_id) 
where db2.courses.id=167 AND db1.questionnaire_question.deleted="n" 
group by db1.questionnaire_quest_choice.id;