Count numbers of checkboxes and update MySQL - php

Question

I'm updating some MySQL data for specific entries selected through checkboxes, my code for that looks like this:
<?php
if($_POST['code_approve']){
for($i=0;$i<count($_POST['checkbox']);$i++){
$approval_id = $checkbox[$i];
$sql = "UPDATE table SET status='approved', used='processed' WHERE id='$approval_id'";
$result = mysql_query($sql);
}
if($result){
echo "<meta http-equiv=\"refresh\" content=\"0;URL=table.php\">";
}
}
?>
Now I want to know how many checkboxes have been selected, and for every checkbox selected add 25 to table "members" row "balance".
I tried like this:
<?php
if($_POST['code_approve']){
for($i=0;$i<count($_POST['checkbox']);$i++){
$approval_id = $checkbox[$i];
$approvedamount = count($_POST['checkbox'])
$approvedx25 = $approvedamount * 25;
$sql = "UPDATE table SET status='approved', used='processed' WHERE id='$approval_id'";
$sql2 = "UPDATE members SET balance = + '$approvedx25'";
$result = mysql_query($sql);
}
if($result){
echo "<meta http-equiv=\"refresh\" content=\"0;URL=table.php\">";
}
}
?>
But that didn't work at all, what's the proper way to do this ?
//EDIT
Please ignore this question, it worked, i just forgot to add the mysql_query.

Answer 1

Your update query should be something like this:
$sql2 = "UPDATE members SET balance = balance + ".$approvedx25;
The way you wrote it, the update in withing the for clause, thus executed once for every checkbox. I'm not sure you want that, since you already multiply by the number of checkboxes.
Also, mind, your second query ($sql2) is not executed in your code.