PHP でのデータ同期関数の使用方法

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

// Check connection
if($mysqli === false){
    die("ERROR: Could not connect. " . $mysqli->connect_error);
}

$sql = "INSERT INTO users (firstname, lastname, email) VALUES ('John', 'Doe', 'john@example.com')";
if($mysqli->query($sql) === true){
    echo "Records inserted successfully.";
} else{
    echo "ERROR: Could not able to execute $sql. " . $mysqli->error;
}

$sql = "SELECT id, firstname, lastname FROM users";
$result = $mysqli->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
    }
} else {
    echo "0 results";
}

$dsn = 'mysql:host=localhost;dbname=database_name';
$username = 'username';
$password = 'password';

try {
    $dbh = new PDO($dsn, $username, $password);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

$sql = "INSERT INTO users (firstname, lastname, email) VALUES (:firstname, :lastname, :email)";
$stmt = $dbh->prepare($sql);
$stmt->bindParam(':firstname', $firstname);
$stmt->bindParam(':lastname', $lastname);
$stmt->bindParam(':email', $email);

// insert a row
$firstname = 'John';
$lastname = 'Doe';
$email = 'john@example.com';
$stmt->execute();

$sql = "SELECT id, firstname, lastname FROM users";
$stmt = $dbh->prepare($sql);
$stmt->execute();

// set the resulting array to associative
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);

foreach ($stmt->fetchAll() as $row) {
    echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
}