<?php

/*** mysql hostname ***/
$hostname = 'localhost';

$dbname = 'dbname';

/*** mysql username ***/
$username = 'username';

/*** mysql password ***/
$password = 'password';

try {
	$dbh = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password);

	$tablename = 'table';

	$sql = 'SHOW COLUMNS FROM `'.$tablename.'`';

	$stmt = $dbh->query($sql);
	$stmt->execute();

	while($row = $stmt->fetch(PDO::FETCH_ASSOC))
	{
		array_push($fields, $row['Field']);
	}

	array_push($csv, $fields);

	$sql = 'SELECT * FROM `'.$tablename.'`';


	$stmt = $dbh->query($sql);
	$stmt->execute();

	$csv = array();

	while($row = $stmt->fetch(PDO::FETCH_NUM))
	{
		array_push($csv, $row);
	}

	$fp = fopen('file.csv', 'w');

	foreach ($csv as $row) {
		fputcsv($fp, $row);
	}

	fclose($fp);

	header("Content-type: application/csv");
	header("Content-Disposition: attachment; filename=export.csv");
	header("Pragma: no-cache");
	header("Expires: 0");

	readfile('file.csv');

	$dbh = null;

} catch(PDOException $e) {
	echo $e->getMessage();
}