The behaviour of these functions is affected by settings in php.ini.
Here's a short explanation of the configuration directives.
The default server host to use when connecting to the database server if no other host is specified.
The default server database to use when connecting if no other database is specified.
The default user name to use when connecting to the database server if no other name is specified.
The default password to use when connecting to the database server if no other password is specified.
The default maximum length of bytes that is transferred to the client if long data is retrieved from the MaxDB database server.