<?php

$servername = "localhost";
$database = "exercise";
$username = "root";
$password = "";

$conn = new PDO("mysql:host=$servername;dbname=$database;charset=utf8mb4", $username, $password);

$fullname = 'Jaylord Ferrer';
$username = 'HardRock';
$password = 'p@55w0rd';

$stmt = $conn->prepare("INSERT INTO users(`fullname`, `username`, `password`) VALUES(?, ?, ?)");
$stmt->execute(array($fullname, $username, $password));