осознал никчёмность, но всё ровно дальше тоже беда.
<?php
$link = mysqli_connect("localhost", "root", "s123", "play_list");
if(mysqli_connect_errno()) {
echo "error, can not to connect to DB (".mysqli_connect_errno()."):" .mysqli_connect_error();
exit();
}
?>
пишет
Fatal error: Uncaught Error: Call to undefined function mysqli_connect() in C:\Apache24\htdocs\dbc.php:3 Stack trace: #0 C:\Apache24\htdocs\index.php(2): require_once() #1 {main} thrown in C:\Apache24\htdocs\dbc.php on line 3