Get value and increment by one for each user - php

Question

I have this script as a cron job set to run every 5 mins, the problem is it will not increment the energy level as I believe it should. If anyone can tell me what I am doing wrong here it would be great.
Remember, this returns no errors, just doesn't work, also the database connect info is all correct, just left out of the post.
{
$energy = mysql_query("SELECT energy FROM members WHERE id=$id");
//get current users energy level
$energy_max = mysql_query("SELECT energy-Max FROM members WHERE id=$id");
//get current users Maximum energy level
if ($energy < $energy_max)
// do -if current energy level is less than maximum
{
$energy = $energy ++;
//increment energy by 1
mysql_query("UPDATE members SET energy= $energy");
//set the new energy level
}
$id++;
//increment to the next user
}

Answer 1

You can solve everything within a single statement
UPDATE `members` SET `energy` = `energy` + 1 WHERE `energy-Max` > `energy`;
This way you have one instead of 3 * number-of-members queries

Answer 2

You forgot the WHERE id = $id in the update Statement.
mysql_query("UPDATE members SET energy= $energy WHERE id = $id");
But KingCrunch's answer is better ..

Answer 3

mysql_query doesn't return values, only so-called query id. You have to fetch actual data:
$query = mysql_query("SELECT energy FROM members WHERE id=$id");
$val = mysql_fetch_assoc($query); // Now the data is in $val['energy']
Of course you can do this quicker, via this (as pointed in other answer):
UPDATE members SET energy = energy + 1 WHERE energy < energy-Max;