distinguish between "-" and "_"

Hello,

I encounter a problem when searching :

SELECT part_number, description FROM part WHERE part_number LIKE
"000-1_GB-01"

and

SELECT part_number, description FROM part WHERE part_number LIKE
"000-1-GB-01"

Both returns "000-1-GB-01". I expect to see the first search returns
"not found" since there's no"000-1_GB-01" in the database, only the
" . 000-1-GB-01".

Why it can't distinguish "-" and "_"? Does this related to
the setting in the database table ?

Thanks.

Lei