mysqli sqlsrv oci8 pgsql ibmdb2 pdo_mysql pdo_pgsql pdo_oci pdo_dblib pdo_sqlsrv A string containing a hostname or IP address of the database server. If the database is running on the same host as the PHP application, you may use 'localhost' or '127.0.0.1'. Account identifier for authenticating a connection to the RDBMS server. Account password credential for authenticating a connection to the RDBMS server. Database instance name on the RDBMS server. Some RDBMS servers can accept network connections on a administrator-specified port number. The port parameter allow you to specify the port to which your PHP application connects, to match the port configured on the RDBMS server. Specify the charset used for the connection.