From 777c2131dd7aeaf25adbbbbb0c213950e852f22b Mon Sep 17 00:00:00 2001
From: Alexander Barkov <bar@mariadb.org>
Date: Sat, 2 Apr 2016 00:04:47 +0400
Subject: [PATCH] MDEV-9862 Illegal mix of collation, when comparing column
 with CASE expression

---
 mysql-test/r/ctype_cp850.result | 14 ++++++++++++++
 mysql-test/t/ctype_cp850.test   | 16 ++++++++++++++++
 sql/item.h                      |  2 +-
 3 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 mysql-test/r/ctype_cp850.result
 create mode 100644 mysql-test/t/ctype_cp850.test

diff --git a/mysql-test/r/ctype_cp850.result b/mysql-test/r/ctype_cp850.result
new file mode 100644
index 00000000000..c028f72b58a
--- /dev/null
+++ b/mysql-test/r/ctype_cp850.result
@@ -0,0 +1,14 @@
+#
+# Start of 5.5 tests
+#
+#
+# MDEV-9862 Illegal mix of collation, when comparing column with CASE expression
+#
+SET NAMES cp850;
+CREATE TABLE t1 (a CHAR(1) CHARACTER SET latin1);
+SELECT a FROM t1 WHERE CASE a WHEN 'aaaa' THEN 'Y' WHEN 'aaaa' THEN 'Y' ELSE NULL END <> a;
+a
+DROP TABLE t1;
+#
+# End of 5.5 tests
+#
diff --git a/mysql-test/t/ctype_cp850.test b/mysql-test/t/ctype_cp850.test
new file mode 100644
index 00000000000..358829eb351
--- /dev/null
+++ b/mysql-test/t/ctype_cp850.test
@@ -0,0 +1,16 @@
+--echo #
+--echo # Start of 5.5 tests
+--echo #
+
+--echo #
+--echo # MDEV-9862 Illegal mix of collation, when comparing column with CASE expression
+--echo #
+SET NAMES cp850;
+CREATE TABLE t1 (a CHAR(1) CHARACTER SET latin1);
+SELECT a FROM t1 WHERE CASE a WHEN 'aaaa' THEN 'Y' WHEN 'aaaa' THEN 'Y' ELSE NULL END <> a;
+DROP TABLE t1;
+
+
+--echo #
+--echo # End of 5.5 tests
+--echo #
diff --git a/sql/item.h b/sql/item.h
index d09f6572487..41e6fe0e38e 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -2175,7 +2175,7 @@ public:
     max_length= 0;
     name= name_par ? name_par : (char*) "NULL";
     fixed= 1;
-    collation.set(&my_charset_bin, DERIVATION_IGNORABLE);
+    collation.set(&my_charset_bin, DERIVATION_IGNORABLE, MY_REPERTOIRE_ASCII);
   }
   enum Type type() const { return NULL_ITEM; }
   bool eq(const Item *item, bool binary_cmp) const;