From 3d47155643e6f34edade6fae5164ae957b8372ca Mon Sep 17 00:00:00 2001
From: Charles Fulton <fultonc@lafayette.edu>
Date: Tue, 11 Aug 2015 12:35:09 +0000
Subject: [PATCH 1/2] MDL-51052 dml: support for sql_like() under utf8_bin

---
 lib/dml/mysqli_native_moodle_database.php | 7 ++++++-
 lib/dml/tests/dml_test.php                | 5 +++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/dml/mysqli_native_moodle_database.php b/lib/dml/mysqli_native_moodle_database.php
index 9d7b7670c32..8c61536809e 100644
--- a/lib/dml/mysqli_native_moodle_database.php
+++ b/lib/dml/mysqli_native_moodle_database.php
@@ -1523,7 +1523,12 @@ class mysqli_native_moodle_database extends moodle_database {
             if ($accentsensitive) {
                 return "LOWER($fieldname) $LIKE LOWER($param) COLLATE utf8_bin ESCAPE '$escapechar'";
             } else {
-                return "$fieldname $LIKE $param ESCAPE '$escapechar'";
+                // Set a case sensitive collation if using utf8_bin.
+                if ($this->get_dbcollation() == 'utf8_bin') {
+                    return "$fieldname $LIKE $param COLLATE utf8_unicode_ci ESCAPE '$escapechar'";
+                } else {
+                    return "$fieldname $LIKE $param ESCAPE '$escapechar'";
+                }
             }
         }
     }
diff --git a/lib/dml/tests/dml_test.php b/lib/dml/tests/dml_test.php
index b064d99aa03..8b165652f0b 100644
--- a/lib/dml/tests/dml_test.php
+++ b/lib/dml/tests/dml_test.php
@@ -3870,6 +3870,11 @@ class core_dml_testcase extends database_driver_testcase {
         $records = $DB->get_records_sql($sql, array('aui'));
         $this->assertCount(1, $records);
 
+        // Test LIKE under unusual collations.
+        $sql = "SELECT * FROM {{$tablename}} WHERE ".$DB->sql_like('name', '?', false, false);
+        $records = $DB->get_records_sql($sql, array("%dup_r%"));
+        $this->assertCount(2, $records);
+
         $sql = "SELECT * FROM {{$tablename}} WHERE ".$DB->sql_like('name', '?', true, true, true); // NOT LIKE.
         $records = $DB->get_records_sql($sql, array("%o%"));
         $this->assertCount(3, $records);

From 2bdeb8ef3026a12daef0f3e4534c101d27c24c57 Mon Sep 17 00:00:00 2001
From: David Monllao <davidm@moodle.com>
Date: Fri, 18 Sep 2015 11:42:12 +0800
Subject: [PATCH 2/2] MDL-51052 dml: More info about mysql and case & accent
 sensitiveness

---
 lib/dml/mysqli_native_moodle_database.php | 28 +++++++++++++++--------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/lib/dml/mysqli_native_moodle_database.php b/lib/dml/mysqli_native_moodle_database.php
index 8c61536809e..70e8a6ed4bc 100644
--- a/lib/dml/mysqli_native_moodle_database.php
+++ b/lib/dml/mysqli_native_moodle_database.php
@@ -1502,10 +1502,13 @@ class mysqli_native_moodle_database extends moodle_database {
     /**
      * Returns 'LIKE' part of a query.
      *
+     * Note that mysql does not support $casesensitive = true and $accentsensitive = false.
+     * More information in http://bugs.mysql.com/bug.php?id=19567.
+     *
      * @param string $fieldname usually name of the table column
      * @param string $param usually bound query parameter (?, :named)
      * @param bool $casesensitive use case sensitive search
-     * @param bool $accensensitive use accent sensitive search (not all databases support accent insensitive)
+     * @param bool $accensensitive use accent sensitive search (ignored if $casesensitive is true)
      * @param bool $notlike true means "NOT LIKE"
      * @param string $escapechar escape char for '%' and '_'
      * @return string SQL code fragment
@@ -1517,19 +1520,24 @@ class mysqli_native_moodle_database extends moodle_database {
         $escapechar = $this->mysqli->real_escape_string($escapechar); // prevents problems with C-style escapes of enclosing '\'
 
         $LIKE = $notlike ? 'NOT LIKE' : 'LIKE';
+
         if ($casesensitive) {
+            // Current MySQL versions do not support case sensitive and accent insensitive.
             return "$fieldname $LIKE $param COLLATE utf8_bin ESCAPE '$escapechar'";
+
+        } else if ($accentsensitive) {
+            // Case insensitive and accent sensitive, we can force a binary comparison once all texts are using the same case.
+            return "LOWER($fieldname) $LIKE LOWER($param) COLLATE utf8_bin ESCAPE '$escapechar'";
+
         } else {
-            if ($accentsensitive) {
-                return "LOWER($fieldname) $LIKE LOWER($param) COLLATE utf8_bin ESCAPE '$escapechar'";
-            } else {
-                // Set a case sensitive collation if using utf8_bin.
-                if ($this->get_dbcollation() == 'utf8_bin') {
-                    return "$fieldname $LIKE $param COLLATE utf8_unicode_ci ESCAPE '$escapechar'";
-                } else {
-                    return "$fieldname $LIKE $param ESCAPE '$escapechar'";
-                }
+            // Case insensitive and accent insensitive.
+            $collation = '';
+            if ($this->get_dbcollation() == 'utf8_bin') {
+                // Force a case insensitive comparison if using utf8_bin.
+                $collation = 'COLLATE utf8_unicode_ci';
             }
+
+            return "$fieldname $LIKE $param $collation ESCAPE '$escapechar'";
         }
     }