int mysql_connect(string [hostname [:port] [:/path/to/socket] ] , string [username] , string [password] );
Returns: A positive MySQL link identifier on success, or false on error.
mysql_connect() establishes a connection to a MySQL server. All of the arguments are optional, and if they're missing, defaults are assumed ('localhost', user name of the user that owns the server process, empty password).
The hostname string can also include a port number. eg. "hostname:port" or a path to a socket eg. ":/path/to/socket" for the localhost.
Note: Support for ":port" wass added in 3.0B4.
Support for the ":/path/to/socket" was added in 3.0.10.
In case a second call is made to mysql_connect() with the same arguments, no new link will be established, but instead, the link identifier of the already opened link will be returned.
The link to the server will be closed as soon as the execution of the script ends, unless it's closed earlier by explicitly calling mysql_close().