From cb94adc252b6e36591965bde40e05749414326fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20S=CC=8Ckoda?= <commits@skodak.org>
Date: Sat, 11 Aug 2012 20:05:56 +0200
Subject: [PATCH] MDL-34776 improve multiple "NOT IN" enrolment and role
 related queries

---
 admin/roles/lib.php       | 10 ++++------
 enrol/locallib.php        | 14 +++++---------
 enrol/manual/locallib.php |  8 +++-----
 user/selector/lib.php     |  5 ++---
 4 files changed, 14 insertions(+), 23 deletions(-)

diff --git a/admin/roles/lib.php b/admin/roles/lib.php
index 11341d10cfe..43eb7f530b8 100644
--- a/admin/roles/lib.php
+++ b/admin/roles/lib.php
@@ -1039,12 +1039,10 @@ class potential_assignees_below_course extends role_assign_user_selector_base {
         $countfields = 'SELECT COUNT(u.id)';
 
         $sql   = " FROM {user} u
-                  WHERE u.id IN ($enrolsql) $wherecondition
-                        AND u.id NOT IN (
-                           SELECT r.userid
-                             FROM {role_assignments} r
-                            WHERE r.contextid = :contextid
-                                  AND r.roleid = :roleid)";
+              LEFT JOIN {role_assignments} ra ON (ra.userid = u.id AND ra.roleid = :roleid AND ra.contextid = :contextid)
+                  WHERE u.id IN ($enrolsql)
+                        $wherecondition
+                        AND ra.id IS NULL";
         $order = ' ORDER BY lastname ASC, firstname ASC';
 
         $params['contextid'] = $this->context->id;
diff --git a/enrol/locallib.php b/enrol/locallib.php
index 30c9db8d1d7..b19a716b2ba 100644
--- a/enrol/locallib.php
+++ b/enrol/locallib.php
@@ -278,7 +278,7 @@ class course_enrolment_manager {
         global $DB, $CFG;
 
         // Add some additional sensible conditions
-        $tests = array("id <> :guestid", 'u.deleted = 0', 'u.confirmed = 1');
+        $tests = array("u.id <> :guestid", 'u.deleted = 0', 'u.confirmed = 1');
         $params = array('guestid' => $CFG->siteguest);
         if (!empty($search)) {
             $conditions = get_extra_user_fields($this->get_context());
@@ -306,10 +306,9 @@ class course_enrolment_manager {
         $fields      = 'SELECT '.$ufields;
         $countfields = 'SELECT COUNT(1)';
         $sql = " FROM {user} u
+            LEFT JOIN {user_enrolments} ue ON (ue.userid = u.id AND ue.enrolid = :enrolid)
                 WHERE $wherecondition
-                      AND u.id NOT IN (SELECT ue.userid
-                                         FROM {user_enrolments} ue
-                                         JOIN {enrol} e ON (e.id = ue.enrolid AND e.id = :enrolid))";
+                      AND ue.id IS NULL";
         $order = ' ORDER BY u.lastname ASC, u.firstname ASC';
         $params['enrolid'] = $enrolid;
         $totalusers = $DB->count_records_sql($countfields . $sql, $params);
@@ -353,12 +352,9 @@ class course_enrolment_manager {
         $fields      = 'SELECT '.user_picture::fields('u', array('username','lastaccess'));
         $countfields = 'SELECT COUNT(u.id)';
         $sql   = " FROM {user} u
+              LEFT JOIN {role_assignments} ra ON (ra.userid = u.id AND ra.contextid = :contextid)
                   WHERE $wherecondition
-                    AND u.id NOT IN (
-                           SELECT u.id
-                             FROM {role_assignments} r, {user} u
-                            WHERE r.contextid = :contextid AND
-                                  u.id = r.userid)";
+                    AND ra.id IS NULL";
         $order = ' ORDER BY lastname ASC, firstname ASC';
 
         $params['contextid'] = $this->context->id;
diff --git a/enrol/manual/locallib.php b/enrol/manual/locallib.php
index 32558827159..1d09681ad12 100644
--- a/enrol/manual/locallib.php
+++ b/enrol/manual/locallib.php
@@ -55,11 +55,9 @@ class enrol_manual_potential_participant extends user_selector_base {
         $countfields = 'SELECT COUNT(1)';
 
         $sql = " FROM {user} u
-                WHERE $wherecondition AND
-                      u.id NOT IN (
-                          SELECT ue.userid
-                            FROM {user_enrolments} ue
-                            JOIN {enrol} e ON (e.id = ue.enrolid AND e.id = :enrolid))";
+            LEFT JOIN {user_enrolments} ue ON (ue.userid = u.id AND ue.enrolid = :enrolid)
+                WHERE $wherecondition
+                      AND ue.id IS NULL";
         $order = ' ORDER BY u.lastname ASC, u.firstname ASC';
 
         if (!$this->is_validating()) {
diff --git a/user/selector/lib.php b/user/selector/lib.php
index 9aa40edf03f..daecbf1e1a0 100644
--- a/user/selector/lib.php
+++ b/user/selector/lib.php
@@ -832,10 +832,9 @@ class group_non_members_selector extends groups_user_selector_base {
                    JOIN ($enrolsql) e ON e.id = u.id
               LEFT JOIN {role_assignments} ra ON (ra.userid = u.id AND ra.contextid " . get_related_contexts_string($context) . " AND ra.roleid $roleids)
               LEFT JOIN {role} r ON r.id = ra.roleid
+              LEFT JOIN {groups_members} gm ON (gm.userid = u.id AND gm.groupid = :groupid)
                   WHERE u.deleted = 0
-                        AND u.id NOT IN (SELECT userid
-                                          FROM {groups_members}
-                                         WHERE groupid = :groupid)
+                        AND gm.id IS NULL
                         AND $searchcondition";
         $orderby = "ORDER BY u.lastname, u.firstname";