check connection error in php code example

Example 1: check network connection php

$response = null;
system("ping -c 1 google.com", $response);
if($response == 0)
{
    // this means you are connected
}

Example 2: mysqli connect error

<?php
$conn=mysqli_connect("localhost","username","password","database_name");
?>

This code will connect with database 'database_name' while $conn is connection name