YOu need to take a look at the php / sql documentation on this. The mysql_connect() function should be called with other variables. See http://us2.php.net/manual/en/function.mysql-connect.php .
Check the variables in phpinfo() , make sure that the proper version is in there. If ou have shell access try to connect to the database from the shell using
mysql -uusername -ppassword database
If that doesn't work, then you have a problem with the user/pass/db connection, not php itself.
This isn't really a geeklog problem, it's a mysql issue, or php compilation issue.
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