connection to mysql By host name not localhost How ? please

i want to connect with mysql database in php code i connect right with mysql_connect('localhost',$username,$password);

if my database in onther server how connect with new server localhost word not working i want to write server name how i can do it

If I understand you correctly, you want localhost for the MySQL port to point to a different server and not actually be local?
If thats the case try searching the forums for "remote mysql"