mysql_query返回类型

$result = mysql_query("SELECT * FROM table_name", $connection);

$mysqli = new mysqli("localhost", "username", "password", "database");

if ($mysqli->connect_error) {
    die("连接失败: " . $mysqli->connect_error);
}

$result = $mysqli->query("SELECT * FROM table_name");

if ($result) {
    while ($row = $result->fetch_assoc()) {
        echo $row['column_name'] . "<br>";
    }
    $result->free();
}

$mysqli->close();

try {
    $pdo = new PDO("mysql:host=localhost;dbname=database", "username", "password");
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $result = $pdo->query("SELECT * FROM table_name");

    while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
        echo $row['column_name'] . "<br>";
    }
} catch (PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}

$pdo = null;