PHP 使用mysql 与 mysqli 连接Mysql数据库

<?php
 
     /**
    * @Author:      HTL
    * @Email:       Huangyuan413026@163.com
    * @DateTime:    2015-05-14 16:00:08
    * @Description: Description
    */
    // 降低PHP默认的错误级别
    // 只显示除禁用以外的所有错误
    // 解决因为PHP5.3+版本太高而导致在使用mysql_connect时出现的弃用警告“Deprecated: mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead”
    error_reporting(E_ALL ^ E_DEPRECATED);
    $db_host="localhost";
    $db_user="root";
    $db_passwd="";
    $db_name="mysql";
    echo("<BR>---------------------------mysql_connect------------------------<BR><BR>");
    $query = "SELECT SESSION_USER(), CURRENT_USER(),now();";
    $conn = mysql_connect($db_host, $db_user,$db_passwd);
    if (!$conn)
    {
      die(‘Could not connect: ‘ . mysql_error());
    }
    mysql_select_db($db_name, $conn);
    $result = mysql_query($query);
    while($row = mysql_fetch_array($result)){
      var_dump($row);
    }
    mysql_close($conn);
    echo("<BR>---------------------------mysqli_connect------------------------<BR><BR>");
    $conn = mysqli_connect($db_host, $db_user, $db_passwd,$db_name) ; 
    if (!$conn)
    {
      die(‘Could not connect: ‘ . mysqli_error());
    }
    //execute the query. 
    $result = mysqli_query($conn, $query); 
    //display information: 
    while($row = mysqli_fetch_array($result)) {
        var_dump($row); 
    } 
    mysqli_close($conn);
    exit();
    
?>