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

  try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $sql = "INSERT INTO MyGuests (firstname, lastname, email)
    VALUES ('John', 'Doe', 'john@example.com')";
    // use exec() because no results are returned
    $conn->exec($sql);
    echo "New record created successfully";
  }
  catch(PDOException $e) {
    echo $sql . "<br>" . $e->getMessage();
  }

  $conn = null;
?>

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

  try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $last_id = $conn->lastInsertId();
    echo "Last inserted ID is: " . $last_id;
  }
  catch(PDOException $e) {
    echo $sql . "<br>" . $e->getMessage();
  }

  $conn = null;
?>

Last inserted ID is: 0

Last inserted ID is: 1