DATEDIFF creating function for php code - php

Question

I am trying to convert the following MYSQL SELECT code in to php code: DATEDIFF(date, NOW()) <= 31 basicaly if the date is less than or equal to 31 days do the rest.
So far what I have done is the following
$today = new DateTime('now');
$date = $row['date'];
$diff = date_diff($date,$today);
and than inside if cycle I have the condition: if ($diff <= 31)
My Sql date column is only specified as a Date not DateTime I am getting the following error and I am wondering how I can get calculated the date only
Warning: date_diff() expects parameter 1 to be DateTime, string given in D:\xampp\htdocs\website\c.php on line 299
bool(false)
Warning: date_diff() expects parameter 1 to be DateTime, string given in D:\xampp\htdocs\website\c.php on line 299
bool(false)
Aditional Information which makes the answers bellow to not be working is that in my SQL query I am preformating the date with DATE_FORMAT(date,'%d %b %Y') as date
Any help will be very welcome. Thanks!

Answer 1

You need to convert the database data to a DateTime object as well before you do date_diff() on it.
$today = new DateTime('now');
$date = new DateTime($row['date']);
$diff = date_diff($date,$today);
Now realize that since $diff is a DateInterval object, and you only care about the days component, you can evaluate like this:
if ($date->days <= 31) {
// do something
}

Answer 2

Try:
$today = new DateTime('now');
$date = new DateTime($row['date']);
$diff = $date->diff($today)->days;
date_diff expects both arguments to be DateTime objects. Thats what it is complaining about.
date_diff or Datetime::diff return a DateInterval, you can get the days from the days member variable

Answer 3

Here is the algorithm:
$then = new DateTime('2010-05-30');//example, you could use $row['date']
$now = new DateTime();//now
$delta = $now->diff($then);
$data = array(
'year' => $delta->y,
'month' => $delta->m,
'day' => $delta->d,
'hour' => $delta->h,
'minute' => $delta->i,
'second' => $delta->s
);
//now
if($data['day'] <= 31)
{
//do the stuff
}