php mysql连接得到错误信息

Posted 2023-02-25

【中文标题】php mysql连接得到错误信息

【英文标题】：php mysql connection get error message

【发布时间】：2015-07-28 03:50:33

【问题描述】：

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 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";
?>

这会返回状态码 500，这是内部服务器错误

但我想知道修复它的错误是什么我怎样才能得到错误消息？

我试过了

$conn = mysql_connect($hostname, $username, $password) or die("无法连接 MySQL");

但它没有返回任何东西。

谁能帮帮我？

【问题讨论】：

MySql 是否正在运行并验证登录凭据？

确保您的服务器正在运行。

使用命令行运行mysql检查用户名和密码

【参考方案1】：

如果您在 localhost 上有密码，则使用密码，否则将其留空

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

【参考方案2】：

你 mysqli_connect() 方法。

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


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

echo "Connected successfully";
?>

【参考方案3】：

第一件事是将连接方法更改为 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();

然后您可以在包含 db.php 页面后将您的 PDO 类扩展到新的类。 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'];
              
          
         

【参考方案4】：

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "mydb";

// Create connection
$conn = mysqli_connect($servername, $username, $password);

// Check connection
if (!$conn) 
    die("Connection failed: " . mysqli_connect_error());

echo "Connected successfully";


// make the current db
$db_selected = mysqli_select_db ( $conn , $dbname );
if (!$db_selected) 
   die ('Can\'t connect to Database : ' . mysql_error());



?>

【讨论】：

如果你可以在 localhost 中运行而不是 password="" 和 username ="root"