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domm (4030)

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Just in case you like to know, I'm currently full-time father of 2 kids, half-time Perl hacker, sort-of DJ, bicyclist, no longer dreadlocked and 33 years old

I'm also head of [], maintainer of the CPANTS [] project, member of the TPF Grants Commitee [] and the YAPC Europe Foundation [].

I've got stuff on CPAN [], held various talks [] and organised YAPC::Europe 2007 in Vienna [].

Journal of domm (4030)

Thursday July 31, 2008
01:18 PM

hatefull mysql

[ #37070 ]


Yesterday I got a "funny" bug report: If the user 'märrie' logs in, she gets the account of user 'marrie'. As the system in question gets it's data from a combination of different sources (SAP, a semi-external single sign on system, some local data) I expected some hellish encoding problems (which would be strange, because we switched the whole system over to utf8 two years ago).

So I start my bug-hunt at the lowest level and connect to the MySQL DB. I do a quick "select username from users where username = 'märrie"' (just for basic sanity checking) and get back:


To cut a long bug-hunt short: MySQL considers 'ä' and 'a' to be the same character (at least when using default utf8 settings) - not only for sorting, where this makes a little bit sense, but also for selecting, which is totally pointless.

The solution: use a collate of 'utf8_bin':
mysql> SELECT 'ä' = 'a' COLLATE utf8_general_ci;

| 'ä' = 'a' COLLATE utf8_general_ci |
| 1 |
1 row in set (0.00 sec)

mysql> SELECT 'ä' = 'a' COLLATE utf8_bin;
| 'ä' = 'a' COLLATE utf8_bin |
| 0 |
1 row in set (0.00 sec)

/me hates MySQL!

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  • $ cd projects/MahDayJobb/
    $ cat sql/schemapatch-00039.sql
    ALTER DATABASE CHARACTER SET = 'utf8' COLLATE = 'utf8_unicode_ci';