Dag vergelijken en berekenen

<?php
$vandaag = date("d");

$verschil = $vandaag - $uitjedatabasedag; 

if($verschil >= 3){

//je database update -1
}

<?php
$vandaag = date("d");
 
$verschil = $vandaag - $uitjedatabasedag; 
 
if($verschil >= 3){
 
//je database update -1
}

$now = time();
$threeDays = (60 * 60 * 24 * 3);
$databaseTime = strtotime('dd mm yyyy');

if (($databaseTime - $now) >= $threeDays) {

    // drie dagen geleden

}

$now = time();
$threeDays = (60 * 60 * 24 * 3);
$databaseTime = strtotime('dd mm yyyy');
 
if (($databaseTime - $now) >= $threeDays) {
 
    // drie dagen geleden
 
}

SELECT * FROM `tabel` WHERE `datum_veld` < DATE_SUB(NOW(), INTERVAL 3 DAY)

SELECT * FROM `tabel` WHERE `datum_veld` < DATE_SUB(NOW(), INTERVAL 3 DAY)