mssql_connect() establishes a connection to a MS SQL server. The servername argument has to be a valid servername that is defined in the 'interfaces' file.
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 mssql_close().
The MS SQL server. It can also include a port number. e.g. hostname:port.
If a second call is made to mssql_connect() with the same arguments, no new link will be established, but instead, the link identifier of the already opened link will be returned. This parameter modifies this behavior and makes mssql_connect() always open a new link, even if mssql_connect() was called before with the same parameters.