SQL Server:

• PostgreSQL 9.1.14
• Ubuntu 12.04.5 LTS

Web Server:

• PHP Version 5.5.22-1+deb.sury.org~precise+1
• Apache/2.2.22 (Ubuntu)
• Moodle 2.8.5+ (Build: 20150424)
• Questionnaire: 2014111002 2.8.2 (Build - 2015031901)
• questionnaire_usergraph (default): yes

In a course using either topics or weeks format add a questionnaire activity to the course and the recent activity block will no longer display activity. Clicking on the 'full activity report' link will result in an 'error reading from database' message. Turning on debugging will give the following output:

```Debug info: ERROR: operator does not exist: bigint = character varying
LINE 5: JOIN mdl_user u ON u.id = qr.username
^
HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts.

SELECT qr.*,
u.id AS useridagain,u.picture,u.firstname,u.lastname,u.firstnamephonetic,u.lastnamephonetic,u.middlename,u.alternatename,u.imagealt,u.email
FROM mdl_questionnaire_response qr
JOIN mdl_user u ON u.id = qr.username

WHERE qr.submitted > $1
AND qr.survey_id = $2

ORDER BY qr.submitted ASC
[array (
0 => 1428712858,
1 => '60',
)]
Error code: dmlreadexception
Stack trace:

line 443 of /lib/dml/moodle_database.php: dml_read_exception thrown
line 244 of /lib/dml/pgsql_native_moodle_database.php: call to moodle_database->query_end()
line 764 of /lib/dml/pgsql_native_moodle_database.php: call to pgsql_native_moodle_database->query_end()
line 793 of /mod/questionnaire/lib.php: call to pgsql_native_moodle_database->get_records_sql()
line 167 of /course/recent.php: call to questionnaire_get_recent_mod_activity()```

Courses without a questionnaire activity function as expected. Attached are images of the block and the activity report page with debugging turned OFF. This has affected 2.8.4 and 2.8.5 that I'm aware of.