Trying to work with TIMEDIFF

[HokieTracks]

I am trying to find the difference between the current datetime and the datetime the user was last active. But for whatever reason the code isn't outputting anything but it doesn't have any errors either.

 

$lastactive = $row_userdata['lastactive'];
$now = date("Y-m-d H:i:s");

$activequery = "SELECT TIMEDIFF('$lastactive','$now') AS '$difference'";
mysql_query($activequery) or die(mysql_error());
echo $difference;

[Ken2k7]

   $activequery = "SELECT TIMEDIFF('$lastactive','$now') AS '$difference'";

You're not making any sense there. Try removing the single quotes around $difference and remove the $ in $difference. :-\

[HokieTracks]

Ok, but then how do I display "difference" in php.

[Ken2k7]

Have you ever displayed a SQL result before? Same way you did with $lastactive.

[HokieTracks]

Ohhh, I see now. AS is putting the result into the table. I thought it was defining the result as a variable.

[Ken2k7]

Not exactly. It just gives the column an alias name for easier reference.

[PFMaBiSmAd]

Executing a second query just to calculate a difference using data from a database kind of defeats the point of using the mysql functions in a query. You should be using the TIMEDIFF() logic in your first SELECT query that is getting $row_userdata['lastactive'].

 

Also the mysql NOW() function does the same thing as your $now php code.