PHP check if date and time has passed 15 minutes - php

Question

I'm having some trouble calculating if time is past 15 minutes, on a date and time in my database. How can I check this?
I have this in my database (example):
2014-01-30 15:29:31
And then I get the date from PHP:
$date = date("Y-m-d H:i:s");
But how can I check if the time has passed 15 minutes, or if it's a different day?
I have this code so far:
$date = date("Y-m-d H:i:s");
$sql = "SELECT date FROM reset WHERE session_id = '".$sessid."' limit 1";
$result = mysql_query($sql);
$value = mysql_fetch_object($result);
$dbdate = $value->date;
$checkdate = strtotime($dbdate);
if ($checkdate - time() > 15 * 60) {
error_log("15 mins passed");
}

Answer 1

You can convert the date to a timestamp with strtotime (which supports the MySQL date format) and then compare it to the current timestamp from time.
$dbtimestamp = strtotime($datefromdb);
if (time() - $dbtimestamp > 15 * 60) {
// 15 mins has passed
}
To compare the dates, you can use date to get the year/month/day from the timestamp and then compare them against the current date.
if (date("Y-m-d", $dbtimestamp) != date("Y-m-d")) {
// different date
}

Answer 2

Using a DateTime object:
$dateTimeObject = new \DateTime($dateString);
//and subtract using an interval
$dateTimeObject->sub(new \DateInterval("PT15M"));
$newDateString = $dateTimeObject->format("Y-m-d H:i:s");

Answer 3

you cans use DATE_FORMAT functions.
$actual_minute = date("i");
$data = mysql_query("SELECT DATE_FORMAT(date,'%i') minutes FROM reset WHERE session_id = '".$sessid."'");
$database_minute = $data{'minutes'};