resource db2_connect    ( string $database   , string $username   , string $password   [, array $options  ] )

db2_connect — Returns a connection to a database

database

For a cataloged connection to a database, database represents the database alias in the DB2 client catalog.

For an uncataloged connection to a database, database represents a complete connection string in the following format: 

DATABASE=database;HOSTNAME=hostname;PORT=port;PROTOCOL=TCPIP;UID=username;PWD=password;
where the parameters represent the following values:
database

The name of the database.

hostname

The hostname or IP address of the database server.

port

The TCP/IP port on which the database is listening for requests.

username

The username with which you are connecting to the database.

password

The password with which you are connecting to the database.