Basic set-up to connect to a database using mysqli
<?php
$dbServername = "localhost"; // For local development
$dbUsername = "root";
$dbPassword = "DBPW";
$dbName = "DBNAME";
$mysqli = new mysqli($dbServername, $dbUsername, $dbPassword, $dbName);
// Connection error check
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}