php mysql连接获取错误消息

这是我的第一个php代码，我正在尝试使用用户名=“root”和密码=“root”连接到数据库

我有一个名为

dbConnection.php的连接文件
详情如下:

<?php
echo "in connection file";
$hostname = "localhost";
$username = "root";
$password = "root";
$db = "ledDB";
echo "<br> db-connection : vars definde ";


//connection to the database
$conn = mysql_connect($hostname, $username, $password)
  or die("Unable to connect to MySQL");
echo "Connected to MySQL<br>";
echo "db-connection : initilize connection ";
mysql_select_db($db);
echo "db-connection : connection done";
// Check connection

echo "Connected successfully";
?>



我在一个名为what.php的文件中调用它：

<?php
echo "Hello";
include "dbConnection.php";
echo "ohhhh";
?>



这将返回状态代码500，这是内部服务器错误

但是我想知道什么是错误来修复它我怎样才能得到错误消息

我试过了

$conn=mysql\u connect（$hostname、$username、$password）
或者死亡（“无法连接到MySQL”）

但它没有返回任何东西

有人能帮我吗？
如果您在本地主机上有密码，请使用密码，否则留空

  $con = mysqli_connect("localhost","root","yourpassword","yourdb");


您可以使用mysqli\u connect（）方法

第一件事是将您的连接方法更改为mysqli或我个人最喜欢的PDO。
PDO示例：

class db extends pdo{
    //Website Variables

    public $sitedb = '';
    public $siteconfig;
    public $sitesettings = array(
        'host'      => 'localhost',
        'database'  => 'yourdb',
        'username'  => 'youruser',
        'password'  => 'yourpass',
    );

    public function __construct(){

        $this->sitedb = new PDO(
            "mysql:host={$this->sitesettings['host']};" .
            "dbname={$this->sitesettings['database']};" .
            "charset=utf8",
            "{$this->sitesettings['username']}",
            "{$this->sitesettings['password']}"
        );

        $this->sitedb->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
    }


}

$db = new db();

然后，在包含db.php页面后，可以将PDO类扩展到新类。
示例选择：

   class yourclass extends db {
           public function SelectUsers() {
                    global $db;
                    $query = <<<SQL
                    SELECT email
                    FROM users
                    WHERE active = :active
   SQL;
           $resource = $db->sitedb->prepare( $query );
           $resource->execute( array (
                  ':active' => 1,
                  ));
            $count = $resource->rowCount();
            foreach($resource as $user){
                    $this->email = $user['email'];
              }
          }
         }

class yourclass扩展了db{
公共函数SelectUsers（）{
全球$db；
$query=execute（数组(
'：活动'=>1，
));
$count=$resource->rowCount（）；
foreach（$resource as$user）{
$this->email=$user['email']；
}
}
}
MySql正在运行吗？登录凭据是否已验证？确保您的服务器正在运行。如果可以在localhost中运行MySql，请使用命令行检查用户名和密码，而不是密码=“password=”和用户名=“root”
class db extends pdo{
    //Website Variables

    public $sitedb = '';
    public $siteconfig;
    public $sitesettings = array(
        'host'      => 'localhost',
        'database'  => 'yourdb',
        'username'  => 'youruser',
        'password'  => 'yourpass',
    );

    public function __construct(){

        $this->sitedb = new PDO(
            "mysql:host={$this->sitesettings['host']};" .
            "dbname={$this->sitesettings['database']};" .
            "charset=utf8",
            "{$this->sitesettings['username']}",
            "{$this->sitesettings['password']}"
        );

        $this->sitedb->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
    }


}

$db = new db();

   class yourclass extends db {
           public function SelectUsers() {
                    global $db;
                    $query = <<<SQL
                    SELECT email
                    FROM users
                    WHERE active = :active
   SQL;
           $resource = $db->sitedb->prepare( $query );
           $resource->execute( array (
                  ':active' => 1,
                  ));
            $count = $resource->rowCount();
            foreach($resource as $user){
                    $this->email = $user['email'];
              }
          }
         }