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

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

You need to either

• use a collation that doesn't have this "feature" (namely utf8_bin, but that has other consequences)

• use a different collation for the query only. This should work:

   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 Ä = A 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 2

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.