Duplicate Entry on varchar field PK?

[Brain Wang]

Hi:

I test this script:

drop table if exists TMP_TEST;
create table TMP_TEST
(
col1 VARCHAR(10) ,
primary key (col1)
);
insert into TMP_TEST values('test');
insert into TMP_TEST values('TEST');

The 2th insert sql will say "Duplicate Entry 'TEST' for key 1",But the 'test' is NOT equale to 'TEST' string!
How to resolve this problem?
Thanks!