Comparing date by php

Question

I want to compare two dates, the first is my current date and the second is a date from database.

When I see both of them they looks identical, but PHP gives me another result. I tried to compare using functions like strcmp. I simplified my code so you can understand it easier.

<?php
$users_day = "20".date("y-m-d");
$looper = 0 ;
$all_users_selection = mysql_query("SELECT * FROM user");
while($user_rows = mysql_fetch_array($all_users_selection) )
{
    if($user_rows['user_lastseen'] != NULL)
    {
        //Getting user lastseen day and hour
        $db_user_date[$looper] = substr(($user_rows['user_lastseen']) ,0 , 10);
        $db_user_curr[$looper] = $user_rows['username'];
        //Comparing day then hour
        if (strcmp($users_day,$db_user_date[$looper]) != 0)
        {
            //Set offline
            $current_user_update = mysql_query("UPDATE user SET user_status = 'offline' WHERE username = '$db_user_curr[$looper]'");
        }
        $looper++;
  }
  ?>

When I try to test variables, for example echo $users_day;, it gives my the 2016-12-24 (my current date) .

Also when I test the dates from database it gives me a date with the same type for example I added:

echo $db_user_date[$looper];

In my while loop and in some case the date was identical 2016-12-24 when i tested echo strcmp($users_day,$db_user_date[$looper]); it gives me -10 which means they are 100% different but they are not!

Any idea ?

http://stackoverflow.com/q/3847736/5695475 here is a similar question with many answers — dading84, Dec 23 '16 at 22:51

score 4 · Accepted Answer · answered Dec 23 '16 at 22:47

4

Convert your dates to time, which is a numeric value, then compare them.

$current = strtotime($users_day)
$db_date = strtotime($db_user_date[$looper])

if($current > $db_date)
{
    ...
}

answered Dec 23 '16 at 22:47

Hicaro

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2
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it works , thanks !! – M-Amr Moussa Dec 23 '16 at 22:51

score 0 · Answer 2 · answered Dec 23 '16 at 22:56

When comparing dates, you should comapre their values, not their string representation. String '01 Jan 2017' is not equal to string '2017-01-01', however, dates are actually equal, right?

Therefore, you need to transform both dates-string into one format so you can compare them safely. The answer by Hicaro handles the problem easily.

Also, consider replacing this whole block of code with a single query:

<?php
mysql_query("UPDATE user SET user_status = 'offline' WHERE DATE(user_lastseen) <> CURDATE()");

So you're setting 'offline' status to all users whose user_lastseen is not equal to today (I assume this is what you're trying to achieve?).

Comparing date by php

2 Answers2