time comparison help

[EchoFool]

I am having problems with my time comparison im trying to work out how much time is left from when some thing started by checking how many minutes have been from the starting point.

 

The length of time it takes is 90 minutes so i tried this:

<?php
$Today = date("d-m-y", time());
$Get = mysql_query("SELECT TotalSold,Time FROM tours WHERE Date='$Today' AND Url='$Url'")
Or die(mysql_error());

$row = mysql_fetch_assoc($Get);
$Time = $row['Time']; // time it started
$TimeNow = date("H:i:s",time()); // server time

//convert to numbers for maths
$Time2 = strtotime($Time);   
$TimeNow2 = strtotime($TimeNow);

$Difference = $Time2 - $TimeNow2;  // subtract the two to find out the diff
$Difference = $Difference / 60; // divide by 60 to turn in to minutes
$Difference = round($Difference); // round to nearest full integer
$TimeLeft = 90 - $Difference;  //subtract that from 90 minutes which is maximum waiting time

 

 

But my $TimeLeft doesn't show a correct time left =/ Any one able to see where my logic went wrong?

 

[thebadbad]

$TimeNow2 - $Time2, not the other way around

[EchoFool]

$TimeNow2 - $Time2, not the other way around

 

Ok tried that and this is what resulted:

 

Started At: 00:06:00   // this was midnight today
City Time: 14:24:46 // this is now 2pm today (14 hours later)
Time Left: 76 minutes.    < < this is the $TimeLeft

[thebadbad]

Since you subtract the difference from 90 (minutes), the difference should be less than 90 minutes obviously. Else; are you sure $row['Time'] is in HH:MM:SS format?

 

Another thing is, this won't work when the span is crossing midnight. Much easier to store timestamps in the DB, since they also contain the date.

[EchoFool]

The $Time variable is coming from the DB ...and yes it is in that format of HH : MM : SS

But the $TimeNow is the "now" instance so i would of thought the php function to get the server time would suffice?

[blinky001]

You need to use the full data in your functions - i.e. pull a bit more from your database. E.g.

 

<?php

$time = '14:26:13';
$date = '2008-09-01';
$timezone = 'GMT';

$new_time = strtotime($date.' '.$time.' '.$timezone);

?>

 

Or better, you should store date and time together (datetime) and then pull them from the database using "SELECT UNIX_TIMESTAMP(`datetime_field`) WHERE ...."

 

 

[EchoFool]

Ok this is getting a bit far from my skill level. How will that make the calculation work exactly?

[thebadbad]

Firstly, your example was bad because of this:

 

Since you subtract the difference from 90 (minutes), the difference should be less than 90 minutes obviously.

 

Secondly,

 

Another thing is, this won't work when the span is crossing midnight. Much easier to store timestamps in the DB, since they also contain the date.

 

An example of the above; a timespan of 40 minutes crossing midnight: $Time is 23:30:00 and $TimeNow is 00:10:00 (the next day compared to $Time). $TimeNow2 - $Time2 would then be negative, because the format doesn't say anything about the date. Edit: That was rubbish.. To solve the problem, you could say (60*60*24) + answer (which is negative) to get the right amount of seconds.

[The Little Guy]

Something like this???

$minutes = 90;
$sql = mysql_query("SELECT * FROM `tableName` WHERE `date` < DATE_SUB(NOW(),INTERVAL $minutes MINUTE)");
while($row = mysql_fetch_array($sql)){
     echo $row['columnName'];
}