From: Ronald Fischer <ronald.fischer@...>
Date: 2007-07-26T20:52:27+09:00
Subject: MySql+UTF8 woes

I am experiencing a strange problem when retrieving Unicode values from
my MySql5 database on Windows. Here is what I have:

* All programs/modules in my application require in the beginning a file containing

		$KCODE='u'
		require 'jcode'

in the beginning, ensuring that "everything is done in Unicode".

* I checked that the MySql database is "as UTF-8 as possible", in
particular
 - in the table editor of the MySql Administrator, the character set
   for the rows is listed as utf8 (with sorting order utf8_general_ci)
 - The "start variables" tab of the Administrator says utf8 for the default
   character set
 - mysql.ini says 
		default-character-set=utf8
 - On the mysql command line, I see

mysql> SHOW VARIABLES LIKE 'character\_set\_%';
+--------------------------+--------+
| Variable_name            | Value  |
+--------------------------+--------+
| character_set_client     | utf8   | 
| character_set_connection | utf8   | 
| character_set_database   | utf8   | 
| character_set_filesystem | binary | 
| character_set_results    | utf8   | 
| character_set_server     | utf8   | 
| character_set_system     | utf8   | 
+--------------------------+--------+
 

Indeed, the following works well:

    When I store (from Ruby, via 'mysql' gem) a UTF-8 string
    into the database, and later retrieve it, I get back exactly
    what I had put in. This works equally well, whether I type
    (using my UTF-8 enabled text editor) the character (for 
    example, a German umlaut) directly into the Ruby string, 
    which I then store, i.e. (table X having only one column)

      sqlstatement="INSERT INTO X VALUES ('�')"
      dbhandle.query(sqlstatement)

    or whether I write the code point in hexadecimal:
 
      uml_o="\xc3\xb6" # �, i.e. German umlaut-o in UTF-8 encoding
      sqlstatement="INSERT INTO X VALUES ('#{uml_o}')"
      dbhandle.query(sqlstatement)

   In both cases, when I retrieve the rows with 
      dbhandle.query("SELECT * FROM X")
   I eventually get back the row with my "�" as a UTF-8 
   2-Byte-sequence C3 B6.

So far OK. But there are several things which do not work:

(1) When I look at the database table using the SQL Administrator,
    I do not see the letter '�', but instead the characters corresponding
    to the Windows ANSI code sequence for C3 and B6 characters.

(2) When I manually enter data into the database using MySql
    Administrator, by submitting the SQL statement
       INSERT INTO X VALUES ('�')
    the � is displayed fine when looking at the table with a SELECT
    using the Administrator, but when I read the table from Ruby, I do
    not get back a 2 byte UTF-8 sequence for the umlaut, but only one 
    byte with hex code F6. Note that this F6 corresponds to the ANSI 
    code for � in Windows.

(3) When I put the unicode data into a file, and use a Java application
    to read the file and write the data into the database (using JDBC), and 
    I look at the database then with MySql Administrator, I can see the 
    German characters; and when I then read them back with my Ruby 
    application, I get it encoded in Windows ANSI, not Unicode.

Observations (1) and (2) could be explained in the way that maybe the 
MySql administrator interface was not written with UTF-8 in minde. What
surprises me more is that when writing data using Java (which is inherently
Unicode aware) and reading it back with Ruby, causes somewhere a conversion
from UTF-8 into Windows ANSI. 

Does someone have experienced a similar problem and can point out a possible
reason for it?


Ronald
-- 
Ronald Fischer <ronald.fischer@venyon.com>
Phone: +49-89-452133-162