UTF8 Chinese String Comparison
Posted by: CL Chuah
Date: September 25, 2009 01:38PM

Hi all,
I have this table

create table test_utf (
a varchar (255) COLLATE utf8_general_ci
);

Then I have this two records,
insert into test_utf (a) values ('飞');
insert into test_utf (a) values ('裎');

So, when i retrieve the records,
select * from test_utf where a='裎';
> The server returns me both '飞' & '裎'.

If I change it to
select * from test_utf where a=_utf8'裎';
> Server returns nil

If I force collation
select * from test_utf where a='飞' COLLATE utf8_general_ci;
> Error Code : 1253
> COLLATION 'utf8_general_ci' is not valid for CHARACTER SET 'latin1'

select * from test_utf where a='飞' COLLATE latin1_swedish_ci;
> Error Code : 1267
> Illegal mix of collations (utf8_general_ci,IMPLICIT) and (latin1_swedish_ci,EXPLICIT) for operation '='

It puzzles me, so I did a simple test
select CONVERT('飞' USING latin1)=CONVERT('裎' USING latin1); -- got 0
select CONVERT('飞' USING utf8)=CONVERT('裎' USING utf8); -- got 1
select CONVERT('飞' USING gb2312)=CONVERT('裎' USING gb2312); -- got 0
select CONVERT('é' USING utf8)=CONVERT('è' USING utf8); -- got 1

So seems like i gotta to do this
select * from test_utf where CONVERT(a USING gb2312)=CONVERT('飞' USING gb2312);
> in order to get my correct result, and UTF8 comparison treat é == è

I suspect it's something to do with collation/ case-sensitivity.
Can someone explain to me:
1) anything wrong with my understanding of UTF8?
2) the right way to store Chinese char into MySQL

P/S: 飞(飞) 裎(裎) is two different words in Chinese, fyi

Thanks!!

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