How to know my username and password in mysql console

i've installed mySQL .. i entered my password , but i can'开发者_开发技巧t remember they've asked me for a username .. is it admin or root ?

i wanna add the username and password to RubyonRails database.yml

i remember i found a command that tells me the username and password in the mysql console .. but can't find it again !

that's the part i wanna add in my database.yml

development:
 adapter: mysql
 database: myprojectname_development
 username: unknown
 password: devrailspassword
 host: localhost

Since i just started development i don't have a database yet, so there is no way of trial and error ( not that i know of )

CREATE USER 'unknown'@'%' IDENTIFIED BY 'devrailspassword';
GRANT ALL PRIVILEGES ON `myprojectname_development`.* TO 'unknown'@'%' WITH GRANT OPTION;