The DSN prefix is mysql:.

The hostname on which the database server resides.

The port number where the database server is listening.

The name of the database.

The MySQL Unix socket (shouldn't be used with host or port).

The character set. See the character set concepts documentation for more information.

Prior to PHP 5.3.6, this element was silently ignored. The same behaviour can be partly replicated with the PDO::MYSQL_ATTR_INIT_COMMAND driver option, as the following example shows.

<?php
$dsn = 'mysql:host=localhost;dbname=testdb';
$username = 'username';
$password = 'password';
$options = array(
    PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
); 
$dbh = new PDO($dsn, $username, $password, $options);
?>