MySQL 连接功能不起作用？

Question

我正在尝试连接到我的数据库，但它显示 mysql_connect 函数出错。

错误是：致命错误：未捕获错误：在 C:\xampp\htdocs\Connect.php:12 中调用未定义函数 mysql_connect() 堆栈跟踪：#0 C:\xampp\htdocs\Test.php(3): require() #1 {main} throw in C:\xampp\htdocs\Connect.php on line 12

连接文件：

<?php  

$db_host = "localhost"; 
// Place the username for the MySQL database here 
$db_username = "root";  
// Place the password for the MySQL database here 
$db_pass = "";  
// Place the name for the MySQL database here 
$db_name = "oscar"; 

// Run the connection here  
$con = mysql_connect("db_host","$db_username","$db_pass");
if (!$con)
{
  die('Could not connect: ' . mysql_error());
}
mysql_select_db("$db_name", $con);
try 
{
 $conn = new PDO("mysql:host=$db_host;dbname=$db_name", $db_username, $db_pass);
// set the PDO error mode to exception
 $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
 echo "Connected successfully"; 
}
catch(PDOException $e)
{
 echo "Connection failed: " . $e->getMessage();
}

?>

文本文件：

<?php
// Connect to the MySQL database  
require "Connect.php"; 
echo "Success";
?>

Answer 1

为什么要同时使用 mysql_connect 甚至 PDO？并且 mysql 已被弃用并且容易受到 sql 注入。

只有此代码才能连接到您的数据库

<?php
$db_host = "localhost";
// Place the username for the MySQL database here
$db_username = "root";
// Place the password for the MySQL database here
$db_pass = "";
// Place the name for the MySQL database here
$db_name = "oscar";


try {
    $conn = new PDO("mysql:host=$db_host;dbname=$db_name", $db_username, $db_pass);
// set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully";
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}

Answer 2

函数 mysql_connect 是一个已弃用的函数。相反，您应该使用 mysqli_connect 阅读更多相关信息 here

以下代码应该有效：

<?php
/**
 * Created by PhpStorm.
 * User: ...
 * Date: 5-12-2017
 * Time: 09:47
 * Database connection.
 */
?>
<?php
define('DB_SERVER', 'localhost');
define('DB_USERNAME', 'admin');
define('DB_PASSWORD', 'admin');
define('DB_DATABASE', 'your_database');
$db = mysqli_connect(DB_SERVER,DB_USERNAME,DB_PASSWORD,DB_DATABASE);

// Check connection
if (mysqli_connect_errno())
{
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
?>

Answer 3

mysql 函数在 php 5.5.0 中已弃用。我已经更改了您的代码中的一些更改。在 mysqli connect 语句中添加了 $ 符号。

$con = mysqli_connect("$db_host","$db_username","$db_pass");
if (!$con)
{
  die('Could not connect: ' . mysqli_error());
}
mysqli_select_db("$db_name", $con);

Answer 4

尝试使用mysqli

<?php
$db_host = "localhost"; 
$db_username = "root"; // Place the username for the MySQL database here 
$db_pass = "";// Place the password for the MySQL database here  
$db_name = "test";// Place the name for the MySQL database here 
$conn = new mysqli($db_host, $db_username, $db_pass,$db_name);

// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
} 
//echo "Connected successfully";
?>

这非常有效。

MySQL 连接功能不起作用？

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