| Bug #66932 | GREATEST produces invalid result if in subquery with utf8_hungarian_ci collation | ||
|---|---|---|---|
| Submitted: | 23 Sep 2012 13:32 | Modified: | 23 Sep 2012 23:18 |
| Reporter: | Marton Balint | Email Updates: | |
| Status: | Verified | Impact on me: | |
| Category: | MySQL Server: Charsets | Severity: | S3 (Non-critical) |
| Version: | 5.5.25a | OS: | Linux |
| Assigned to: | CPU Architecture: | Any | |
| Tags: | collation, GREATEST, LEAST, subquery, utf8 | ||
[23 Sep 2012 13:37]
Marton Balint
Disregard the workaround. It resets the collation, which seems to be the root cause of this problem.
[23 Sep 2012 14:05]
Peter Laursen
I get same on 5.5.23 using "SET NAMES utf8 COLLATE utf8_danish_ci;" and even "SET NAMES utf8 COLLATE utf8_unicode_ci;" - but with "SET NAMES utf8 COLLATE utf8_general_ci;" expected results are returned. Peter (not a MySQL/Oracle person)
[23 Sep 2012 14:07]
Peter Laursen
5.1.63 returns expect result with all collations.
[23 Sep 2012 14:11]
Peter Laursen
.. and 5.6.6 not affected either.
[23 Sep 2012 23:18]
MySQL Verification Team
Thank you for the bug report.
d:\dbs>d:\dbs\5.5\bin\mysql -uroot --port=3541 --prompt="mysql 5.5 >"
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.5.29 Source distribution
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql 5.5 >use test
Database changed
mysql 5.5 >SET NAMES utf8 COLLATE utf8_hungarian_ci;
Query OK, 0 rows affected (0.00 sec)
mysql 5.5 >
mysql 5.5 >DROP TABLE IF EXISTS `mysqlbug`;
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql 5.5 >
mysql 5.5 >CREATE TABLE `mysqlbug` (
-> `date1` date NOT NULL,
-> `date2` date NOT NULL
-> ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_hungarian_ci;
Query OK, 0 rows affected (0.04 sec)
mysql 5.5 >
mysql 5.5 >INSERT INTO `mysqlbug` (`date1`, `date2`) VALUES ('2000-01-01', '2012-09-01');
Query OK, 1 row affected (0.09 sec)
mysql 5.5 >
mysql 5.5 >SELECT * FROM
-> (
-> SELECT
-> GREATEST(mysqlbug.`date1`, mysqlbug.`date2`) AS `badcolumn`
-> FROM
-> mysqlbug
-> ) AS `badtable`;
+-----------+
| badcolumn |
+-----------+
| 201 |
+-----------+
1 row in set (0.03 sec)
mysql 5.5 >
---------------------------------------------------------------------------------------
d:\dbs>d:\dbs\5.6\bin\mysql -uroot --port=3540 --prompt="mysql 5.6 >"
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.7.0-m10 Source distribution
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql 5.6 >use test
Database changed
mysql 5.6 >SET NAMES utf8 COLLATE utf8_hungarian_ci;
Query OK, 0 rows affected (0.03 sec)
mysql 5.6 >
mysql 5.6 >DROP TABLE IF EXISTS `mysqlbug`;
Query OK, 0 rows affected, 1 warning (0.04 sec)
mysql 5.6 >
mysql 5.6 >CREATE TABLE `mysqlbug` (
-> `date1` date NOT NULL,
-> `date2` date NOT NULL
-> ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_hungarian_ci;
Query OK, 0 rows affected (0.10 sec)
mysql 5.6 >
mysql 5.6 >INSERT INTO `mysqlbug` (`date1`, `date2`) VALUES ('2000-01-01', '2012-09-01');
Query OK, 1 row affected (0.02 sec)
mysql 5.6 >
mysql 5.6 >SELECT * FROM
-> (
-> SELECT
-> GREATEST(mysqlbug.`date1`, mysqlbug.`date2`) AS `badcolumn`
-> FROM
-> mysqlbug
-> ) AS `badtable`;
+------------+
| badcolumn |
+------------+
| 2012-09-01 |
+------------+
1 row in set (0.05 sec)
Description: If the UTF8 charset is set with SET NAMES, the GREATEST (or LEAST) expression in a subquery produces invalid results. On the other hand, if the connection charset is explicitly set, the issue does not occur. How to repeat: SET NAMES utf8 COLLATE utf8_hungarian_ci; DROP TABLE IF EXISTS `mysqlbug`; CREATE TABLE `mysqlbug` ( `date1` date NOT NULL, `date2` date NOT NULL ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_hungarian_ci; INSERT INTO `mysqlbug` (`date1`, `date2`) VALUES ('2000-01-01', '2012-09-01'); SELECT * FROM ( SELECT GREATEST(mysqlbug.`date1`, mysqlbug.`date2`) AS `badcolumn` FROM mysqlbug ) AS `badtable`; The result is: badcolumn 201 Expected result: badcolumn 2012-09-01 Suggested fix: A workaround is to set connection charset explicitly: SET character_set_connection = utf8;