This is a function that I wrote to get an age in years from a mysql style (yyyy-mm-dd) date. Using php's date() function wouldn't work for me out of the box becaus the dates to be stored in the database were mostly pre-1970, and so were represented as negative seconds in relation to 1/1/1970 (the Unix Epoch). This was simpler for me.

MySQL has date features that work from year 0, so that works fine too.

/*I have the echo's in the function just for debug uses */
function mysql_to_timestamp($bday) {
	# This puts our sql date into an array:
	$darray = explode('-', $bday); # 1965-08-28
	
	# mktime with no args returns seconds since Epoch
	$today = mktime();
	 echo "today: $today";
	 
	# now we convert sql date to mktime date 
	# (seconds from Epoch) and echo it
	$age = mktime(0, 0, 0, $darray[1], $darray[2], $darray[0]);
	 echo "age: $age";
	# Subtract bday from today into var $tmp, echo it to screen
	$tmp = ($today - $age);
	 echo "today-age: $tmp";
	 
	# 86400 seconds in a day
	$age = $tmp / 86400;
	 echo "div by 86400: $age";
	
	# Divide the days by 365 and we have years of age,
	# floor() deletes the stuff after the decimal. We don't
	# wanna be 36.43 years old, right
	$age = floor($age / 365);
	 echo "div by 365: $age";
	
	# all that for this
	return $age;
}