php soustraire minutes à datetime
$datetime_from = date("Y-m-d H:i", strtotime("-45 minutes", strtotime($thestime)));
min fonction en php
<?php
echo(min(2,4,6,8,10) . "<br>"); # output: 2
echo(min(22,14,68,18,15) . "<br>"); # output: 14
echo(min(array(4,6,8,10)) . "<br>"); # output: 4
echo(min(array(44,16,81,12))); # output: 12
?>