As admin:

• Create a course with two empty group
• Create a quizz
  As student:
• Attempt the quizz
  As admin:
• View the result > Select an empty group

SQL error is displayed:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') AND qa.preview = 0 AND qa.id IS NOT NULL' at line 1

SELECT COUNT(DISTINCT(CONCAT(u.id,'#',COALESCE(qa.attempt, 0)))) FROM mdl_user u LEFT JOIN mdl_quiz_attempts qa ON qa.userid = u.id AND qa.quiz = 7 WHERE u.id IN () AND qa.preview = 0 AND qa.id IS NOT NULL

• line 686 of lib\dmllib.php: call to debugging()
• line 379 of lib\dmllib.php: call to get_recordset_sql()
• line 396 of mod\quiz\report\overview\report.php: call to count_records_sql()
• line 73 of mod\quiz\report.php: call to quiz_report->display()

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') AND qa.preview = 0 AND qa.id IS NOT NULL' at line 1

SELECT COUNT(DISTINCT(CONCAT(u.id,'#',COALESCE(qa.attempt, 0)))) FROM mdl_user u LEFT JOIN mdl_quiz_attempts qa ON qa.userid = u.id AND qa.quiz = 7 WHERE u.id IN () AND qa.preview = 0 AND qa.id IS NOT NULL

• line 686 of lib\dmllib.php: call to debugging()
• line 379 of lib\dmllib.php: call to get_recordset_sql()
• line 400 of mod\quiz\report\overview\report.php: call to count_records_sql()
• line 73 of mod\quiz\report.php: call to quiz_report->display()

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') AND qa.preview = 0 AND qa.id IS NOT NULL ORDER BY uniqueid LIMIT 30' at line 1

SELECT CONCAT(u.id,'#', IFNULL(qa.attempt, 0) ) AS uniqueid, (SELECT id FROM mdl_quiz_attempts WHERE quiz = 7 AND u.id = userid ORDER BY sumgrades DESC, timestart ASC LIMIT 1)=qa.id AS gradedattempt, qa.uniqueid AS attemptuniqueid, qa.id AS attempt, u.id AS userid, u.idnumber, u.firstname, u.lastname, u.picture, qa.sumgrades, qa.timefinish, qa.timestart, qa.timefinish - qa.timestart AS duration FROM mdl_user u LEFT JOIN mdl_quiz_attempts qa ON qa.userid = u.id AND qa.quiz = 7 WHERE u.id IN () AND qa.preview = 0 AND qa.id IS NOT NULL ORDER BY uniqueid

• line 686 of lib\dmllib.php: call to debugging()
• line 966 of lib\dmllib.php: call to get_recordset_sql()
• line 410 of mod\quiz\report\overview\report.php: call to get_records_sql()
• line 73 of mod\quiz\report.php: call to quiz_report->display()