php连接mysql 编码

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

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

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

// 设置字符集
$conn->set_charset("utf8mb4");

// 执行查询
$sql = "SELECT id, name FROM mytable";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 输出数据
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }
} else {
    echo "0 结果";
}
$conn->close();
?>

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

try {
    $dsn = "mysql:host=$servername;dbname=$dbname;charset=utf8mb4";
    $conn = new PDO($dsn, $username, $password);
    // 设置 PDO 错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 执行查询
    $sql = "SELECT id, name FROM mytable";
    $stmt = $conn->query($sql);

    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. "<br>";
    }
} catch(PDOException $e) {
    echo "连接失败: " . $e->getMessage();
}

$conn = null;
?>