PHP connection mysql database connection test file_PHP tutorial

[php] 
  define("RelativePath", "."); 
  include_once(RelativePath."/DB_mysql.class.php"); # DB_mysql.class.php 在我的资源里面  
  $db_mysql = new DB_mysql();  www.2cto.com
  $db_mysql->set_values("localhost","***","***","***"); 
  # eg: "localhost","root","","test" 
  # eg: "localhost或远程IP地址","root","","test" 
  $link = mysql_connect($db_mysql->mysql_remote_db_host,$db_mysql->mysql_remote_db_username,$db_mysql->mysql_remote_db_password); 
  if(!$link){ 
    die("Not connectted:".mysql_error($link)); 
  } 
  $db_selected = mysql_select_db($db_mysql->mysql_remote_db_name,$link); 
  if(!$db_selected){ 
    die("Can't use ".$db_mysql->mysql_remote_db_name." "."错误提示为"." ".mysql_error($db_selected)); 
  } 
  /*
  else{
    echo "已经成功选择:"." ".$db_mysql->mysql_remote_db_name;
  }
  */ 
  $sql = "select user_id,user_email from user_info limit 100"; 
  $query = mysql_query($sql,$link);  
  if(!$query){ 
    die(mysql_error($query)); 
  } 
  else{ 
    # $num_rows = mysql_num_rows($query); 
    # echo $num_rows; 
    echo mysql_num_rows($query); # the result is 100 
  }     
?>