MySQL treats ÅÄÖ as AAO?!

Question

These two querys gives me the exact same result:

select * from topics where name='Harligt';
select * from topics where name='Härligt';

How is this possible? Seems like mysql translates åäö to aao when it searches. Is there some way to turn this off?

I use utf-8 encoding everywhere as far as i know. The same problem occurs both from terminal and from php.

Answer 1

you want to check your collation settings, collation is the property that sets which characters are identical.

these 2 pages should help you

http://dev.mysql.com/doc/refman/5.1/en/charset-general.html

http://dev.mysql.com/doc/refman/5.1/en/charset-mysql.html

Answer 2

Yes, this is standard behaviour in the non-language-specific unicode collations.

9.1.13.1. Unicode Character Sets

To further illustrate, the following equalities hold in both utf8_general_ci and utf8_unicode_ci (for the effect this has in comparisons or when doing searches, see Section 9.1.7.7, “Examples of the Effect of Collation”):

Ä = A Ö = O Ü = U

See also Examples of the effect of collation

A workaround would be using a different collation for the comparison, I'm looking up some links right now.

Update:

I can't test myself right now but applying the utf8_bin collation to your SELECT should block the implicit Umlaut conversion for that query only:

select * from topics where name='Harligt' COLLATE utf8_bin;

it becomes more difficult if you want to do a case-insensitive LIKE but not have the umlaut conversion. I know no mySQL collation that is case insensitive and does not do this kind of implicit umlaut conversion. If anybody knows one, I'd be interested to hear about it.

Related:

• Looking for case insensitive MySQL collation where “a” != “ä”
• MYSQL case sensitive search for utf8_bin field

Answer 3

Since you are in Sweden I'd recommend using the Swedish collation. Here's an example showing the difference it makes:

CREATE TABLE topics (name varchar(100) not null) CHARACTER SET utf8;

INSERT topics (name) VALUES ('Härligt');

select * from topics where name='Harligt';
'Härligt'

select * from topics where name='Härligt';
'Härligt'    

ALTER TABLE topics MODIFY name VARCHAR(100) CHARACTER SET utf8 COLLATE utf8_swedish_ci;

select * from topics where name='Harligt';
<no results>

select * from topics where name='Härligt';
'Härligt'

Note that in this example I only changed the one column to Swedish collation, but you should probably do it for your entire database, all tables, all varchar columns.