Exportation du tableau vers CSV via le bouton php

Nous sommes en 2017 et mysqli est plus courant que mysql maintenant. Voici donc une version mysqli de la réponse de Josh Liptzin :

<?php

/* Attempt MySQL server connection. */  
$connection = mysqli_connect($database_server, $database_username, $database_password, $database_name);

// Check connection
if($connection === false){
    die("ERROR: Could not connect. " . mysqli_connect_error());
}

$query = "SELECT * FROM Employee_data";
$result = mysqli_query($connection, $query);

$number_of_fields = mysqli_num_fields($result);
$headers = array();
for ($i = 0; $i < $number_of_fields; $i++) {
    $headers[] = mysqli_field_name($result , $i);
}
$fp = fopen('php://output', 'w');
if ($fp && $result) {
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="export.csv"');
    header('Pragma: no-cache');
    header('Expires: 0');
    fputcsv($fp, $headers);
    while ($row = $result->fetch_array(MYSQLI_NUM)) {
        fputcsv($fp, array_values($row));
    }
    die;
}

function mysqli_field_name($result, $field_offset)
{
    $properties = mysqli_fetch_field_direct($result, $field_offset);
    return is_object($properties) ? $properties->name : null;
}

?>