<?php

$conn = mysql_connect('MYSQL_HOST', 'MYSQL_USERNAME', 'MYSQL_PASSWORD') or die(mysql_error());
mysql_select_db('MYSQL_DATABASE', $conn) or die(mysql_error($conn));


$query = sprintf('SELECT * FROM MYSQL_TABLE');
$result = mysql_query($query, $conn) or die(mysql_error($conn));


header('Content-Type: text/csv');
header('Content-Disposition: attachment;filename=export.csv');


$row = mysql_fetch_assoc($result);
if ($row) {
    echocsv(array_keys($row));
}


while ($row) {
    echocsv($row);
    $row = mysql_fetch_assoc($result);
}

function echocsv($fields)
{
    $separator = '';
    foreach ($fields as $field) {
        if (preg_match('/\\r|\\n|,|"/', $field)) {
            $field = '"' . str_replace('"', '""', $field) . '"';
        }
        echo $separator . $field;
        $separator = ',';
    }
    echo "\r\n";
}
?>