PHP implementation of mysql's TO_DAYS() and FROM_DAYS() functions

to-days.php

<?php

function TO_DAYS($date) {
	if (is_numeric($date)) {
		$res = 719528 + (int) ($date / 86400);
	} else {
		$TZ = date_default_timezone_get();
		date_default_timezone_set('UTC');
		$res = 719528 + (int) (strtotime($date) / 86400);
		date_default_timezone_set($TZ);
	}
	return $res;
}

function FROM_DAYS($daystamp, $asTS = false) {
	$ts = ($daystamp - 719528) * 86400;
	return $asTS?$ts:gmdate('Y-m-d', $ts);
}