strtotime problem!

[influx]

How do I find the number of seconds from a certain date to the current?

I have logged in my database a completion date within the past year and I want to figure out how many seconds it has been since the completion date until now.

I know the strtotime command is fairly versatile and I have tried the following without the right conclusion:

strtotime("since ".$completion_date);
//and
strtotime("from ".$completion_date);

What do I need to do to fix this?

thanks.

[bubblenut]

//assuming $completion_date is a text formatted date
$since = time() - strtotime($completion_date);
//assuming $completion_date is a UNIX timestamp
$since = time() - $completion_date;

[goldlikesnow]

<?
$dateTime = "2005-07-31 10:57:42";
//convert to timestamp
$timestamp = strtotime($dateTime);
//timestamp now
$now = time();
$remainder = $now - $timestamp;
?>

[influx]

thanks fellas