Improve score retrieval

db.go

@@ -156,7 +156,7 @@ CREATE TABLE IF NOT EXISTS student_corrected(
 		return err
 	}
 	if _, err := db.Exec(`
-CREATE VIEW IF NOT EXISTS student_scores AS SELECT U.id_user, id_survey, Q.id_question, MAX(R.score) as score FROM survey_quests Q CROSS JOIN users U LEFT JOIN survey_responses R ON Q.id_question = R.id_question AND R.id_user = U.id_user GROUP BY Q.id_question, U.id_user;
+CREATE VIEW IF NOT EXISTS student_scores AS SELECT T.id_user, T.id_survey, Q.id_question, MAX(R.score) AS score FROM (SELECT DISTINCT R.id_user, S.id_survey FROM survey_responses R INNER JOIN survey_quests Q ON R.id_question = Q.id_question INNER JOIN surveys S ON Q.id_survey = S.id_survey) T LEFT OUTER JOIN survey_quests Q ON T.id_survey = Q.id_survey LEFT OUTER JOIN survey_responses R ON R.id_user = T.id_user AND Q.id_question = R.id_question GROUP BY id_user, id_survey, id_question;
 `); err != nil {
 		return err
 	}