PHP语言如何访问mysql数据库

$servername = "数据库服务器地址";
$username = "用户名";
$password = "密码";
$dbname = "数据库名";

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

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

// 执行SQL查询
$sql = "SELECT * FROM 表名";
$result = $conn->query($sql);

// 处理查询结果
if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"] . ", name: " . $row["name"];
    }
} else {
    echo "没有结果";
}

// 关闭连接
$conn->close();

$servername = "数据库服务器地址";
$username = "用户名";
$password = "密码";
$dbname = "数据库名";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    
    // 执行SQL查询
    $sql = "SELECT * FROM 表名";
    $result = $conn->query($sql);
    
    // 处理查询结果
    if ($result->rowCount() > 0) {
        while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
            echo "id: " . $row["id"] . ", name: " . $row["name"];
        }
    } else {
        echo "没有结果";
    }
    
    // 关闭连接
    $conn = null;
} catch(PDOException $e) {
    echo "连接失败: " . $e->getMessage();
}