如何从数据库和DateTime中区分记录

i try to make a diff between record from database and DateTime

this is my code

<?php
$link = mysqli_connect("localhost", "root", "", "abb");
$result = mysqli_query($link, "SELECT * FROM submission_abb");
$row=mysqli_fetch_array($result);
$submission = $row['submission'];
$selesai = new DateTime();
$hitung = $submission->diff($selesai);
$result = $hitung->format('Y-m-d');
if($hitung->d <=3){
echo $result . "Ontime";
}else{
echo $result . "Over time";
}
?>

Your problem is you are calling diff() on a string value as $submission holds a date value which is a string. You can only call diff() on a DateTime() object.

<?php
$link = mysqli_connect("localhost", "root", "", "abb");
$result = mysqli_query($link, "SELECT * FROM submission_abb");
$row=mysqli_fetch_array($result);
$submission = new DateTime($row['submission']);
$selesai = new DateTime();
$hitung = $submission->diff($selesai);
$result = $hitung->format('Y-m-d');
if($hitung->d <=3){
echo $result . "Ontime";
}else{
echo $result . "Over time";
}
?>