A modern version of connecting to the database of bathhouses (php)?

Question

PHP

I saw these options:

<?php
function cont_load()
{
$loading= mysqli_connect('localhost', 'root', '', 'user_site');
$result= mysqli_query($loading, "SELECT content FROM `posting` WHERE id=1");
while ($a= mysqli_fetch_array($result)) {
        echo $a['content'] . "<br />";
}
mysqli_close($loading);
}
?>

<?php
  //Константы для соединения с базой данных
  define('HOST', 'localhost'); //путь к серверу базы данных
  define('USER', 'root');
  define('PASSWORD', '');
  define('DB', 'minicms');
?>

Which option is best, and is it possible to use only one of the methods and not waste time studying other methods in detail?
Maybe there are other options not listed here by me?

Answer 1

www.phptherightway.com/#databases