php的辅助函数功能

<?php
    $link=mysql_connect("localhost","root","root") or die("couldn't connect:".mysql_error());
    echo "字符集的名称： ".mysql_client_encoding()."<br>";
    echo "mysql服务器信息：  ".mysql_get_server_info()."<br>";
    echo "mysql主机信息：  ".mysql_get_host_info()."<br>";
    echo "mysql客户机信息：  ".mysql_get_client_info()."<br>";
    echo "当前系统的状态：  ".mysql_stat()."<br>";
    mysql_close();
?>