PHP データベース接続の落とし穴: よくある間違いや誤解を避ける

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

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接错误
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
} 

// 使用数据库
$sql = "SELECT * FROM table_name";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 在这里处理结果
} else {
    echo "没有结果";
}

// 关闭连接
$conn->close();
?>

<?php
$dsn = "mysql:host=localhost;dbname=database_name";
$username = "username";
$password = "password";

// 创建连接
try {
    $conn = new PDO($dsn, $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e) {
    die("连接失败: " . $e->getMessage());
}

// 使用数据库
$stmt = $conn->prepare("SELECT * FROM table_name");
$stmt->execute();

foreach ($stmt->fetchAll() as $row) {
    // 在这里处理结果
}

// 关闭连接
$conn = null;
?>

<?php
// 远程数据库服务器信息
$servername = "remote.example.com";
$username = "remote_username";
$password = "remote_password";
$dbname = "remote_database_name";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 使用数据库
echo "连接至远程数据库成功！";

// 关闭连接
$conn->close();
?>