diff --git a/lib/db/install.xml b/lib/db/install.xml
index 44a5e65bce8..809ff5ec733 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="lib/db" VERSION="20150922" COMMENT="XMLDB file for core Moodle tables"
+<XMLDB PATH="lib/db" VERSION="20160804" COMMENT="XMLDB file for core Moodle tables"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../lib/xmldb/xmldb.xsd"
 >
@@ -1352,9 +1352,6 @@
         <KEY NAME="primary" TYPE="primary" FIELDS="id"/>
         <KEY NAME="attemptstepid" TYPE="foreign" FIELDS="attemptstepid" REFTABLE="question_attempt_steps" REFFIELDS="id"/>
       </KEYS>
-      <INDEXES>
-        <INDEX NAME="attemptstepid-name" UNIQUE="true" FIELDS="attemptstepid, name"/>
-      </INDEXES>
     </TABLE>
     <TABLE NAME="question_statistics" COMMENT="Statistics for individual questions used in an activity.">
       <FIELDS>
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 64fe2567f95..e2dff5017b7 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -4700,5 +4700,20 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2015111605.07);
     }
 
+    if ($oldversion < 2015111606.01) {
+
+        // Define index attemptstepid-name (unique) to be dropped from question_attempt_step_data.
+        $table = new xmldb_table('question_attempt_step_data');
+        $index = new xmldb_index('attemptstepid-name', XMLDB_INDEX_UNIQUE, array('attemptstepid', 'name'));
+
+        // Conditionally launch drop index attemptstepid-name.
+        if ($dbman->index_exists($table, $index)) {
+            $dbman->drop_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2015111606.01);
+    }
+
     return true;
 }
diff --git a/question/engine/datalib.php b/question/engine/datalib.php
index 0731252ff0b..a30b54bba76 100644
--- a/question/engine/datalib.php
+++ b/question/engine/datalib.php
@@ -287,10 +287,19 @@ class question_engine_data_mapper {
      */
     public function update_question_attempt_metadata(question_attempt $qa, array $names) {
         global $DB;
-        list($condition, $params) = $DB->get_in_or_equal($names);
-        $params[] = $qa->get_step(0)->get_id();
+        if (!$names) {
+            return [];
+        }
+        // Use case-sensitive LIKE instead of get_in_or_equal.
+        // Some databases may use case-insensitive collation, we don't want to delete 'X' instead of 'x'.
+        $sqls = [];
+        $params = [$qa->get_step(0)->get_id()];
+        foreach ($names as $name) {
+            $sqls[] = $DB->sql_like('name', '?', true);
+            $params[] = $DB->sql_like_escape($name);
+        }
         $DB->delete_records_select('question_attempt_step_data',
-                'name ' . $condition . ' AND attemptstepid = ?', $params);
+            'attemptstepid = ? AND (' . join(' OR ', $sqls) . ')', $params);
         return $this->insert_question_attempt_metadata($qa, $names);
     }
 
diff --git a/question/type/calculated/questiontype.php b/question/type/calculated/questiontype.php
index 896def424f5..4426c6205e6 100644
--- a/question/type/calculated/questiontype.php
+++ b/question/type/calculated/questiontype.php
@@ -281,9 +281,9 @@ class qtype_calculated extends question_type {
                 if ($sharedatasetdefs = $DB->get_records_select(
                     'question_dataset_definitions',
                     "type = '1'
-                    AND name = ?
+                    AND " . $DB->sql_like('name', '?') . "
                     AND category = ?
-                    ORDER BY id DESC ", array($dataset->name, $question->category)
+                    ORDER BY id DESC ", array($DB->sql_like_escape($dataset->name), $question->category)
                 )) { // So there is at least one.
                     $sharedatasetdef = array_shift($sharedatasetdefs);
                     if ($sharedatasetdef->options ==  $datasetdef->options) {// Identical so use it.
@@ -1400,9 +1400,9 @@ class qtype_calculated extends question_type {
                 // can manage to automatically take care of
                 // some possible realtime concurrence.
                 if ($olderdatasetdefs = $DB->get_records_select('question_dataset_definitions',
-                        "type = ? AND name = ? AND category = ? AND id < ?
+                        "type = ? AND " . $DB->sql_like('name', '?') . " AND category = ? AND id < ?
                         ORDER BY id DESC",
-                        array($datasetdef->type, $datasetdef->name,
+                        array($datasetdef->type, $DB->sql_like_escape($datasetdef->name),
                                 $datasetdef->category, $datasetdef->id))) {
 
                     while ($olderdatasetdef = array_shift($olderdatasetdefs)) {
@@ -1484,8 +1484,9 @@ class qtype_calculated extends question_type {
             // Construct question local options.
             $sql = "SELECT a.*
                 FROM {question_dataset_definitions} a, {question_datasets} b
-               WHERE a.id = b.datasetdefinition AND a.type = '1' AND b.question = ? AND a.name = ?";
-            $currentdatasetdef = $DB->get_record_sql($sql, array($form->id, $name));
+               WHERE a.id = b.datasetdefinition AND a.type = '1' AND b.question = ? AND ".
+                $DB->sql_like('a.name', '?');
+            $currentdatasetdef = $DB->get_record_sql($sql, array($form->id, $DB->sql_like_escape($name)));
             if (!$currentdatasetdef) {
                 $currentdatasetdef = new stdClass();
                 $currentdatasetdef->type = '0';
@@ -1506,7 +1507,7 @@ class qtype_calculated extends question_type {
             WHERE a.id = b.datasetdefinition
             AND a.type = '1'
             AND a.category = ?
-            AND a.name = ?", array($form->category, $name));
+            AND " . $DB->sql_like('a.name', '?'), array($form->category, $DB->sql_like_escape($name)));
         $type = 1;
         $key = "{$type}-{$form->category}-{$name}";
         if (!empty($categorydatasetdefs)) {
diff --git a/version.php b/version.php
index 13337212ccf..40e27515841 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2015111606.00;              // 20151116      = branching date YYYYMMDD - do not modify!
+$version  = 2015111606.01;              // 20151116      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.