MySQL update in a PHP While loop - php

Question

I almost finished a site which stores and lets admins manipulate user information.
The last function I implemented was the ability to modify rankings: every user has a rank, and you can use a menu to manually adjust it by moving users up or down.
It works perfectly: I can modify it, the database stores the new rankings correctly; I can add a new user and it becomes the lowest ranked one. The problem is when I try to delete a user.
I wrote a PHP script, which should do the following:
Receive the user's ID
Remove the user's data from two table by using a WHERE statement
Remove the user's uploaded file from the server
Update the other users' rank, so if I deleted the 3rd user, the previously 4th becomes the 3rd, the 5th will be the new 4th and so on. This last part is where my code doesn't work.
Here is the whole PHP:
<?php
// Connecting to the server.
$con=mysqli_connect("connection data");
$rangcounter = 1;
//deleting the user's data - works: the user's data is deleted from both tables
if($_SERVER['REQUEST_METHOD'] == 'POST'){
$id = $_POST['playerid'];
mysqli_query($con,"DELETE FROM Player WHERE ID=$id");
mysqli_query($con,"DELETE FROM Troops WHERE ID=$id");
}
//deleting the user's image from the server - works: the user's file is deleted
$directory = 'uploads/';
unlink($directory . $id . "picture.jpg");
//updating the database - does not work: the other users' ranks stay the same as before
$result = mysqli_query($con,"SELECT * FROM Player ORDER BY rank ASC");
while($row = mysqli_fetch_array($result)) {
$updateid = $row['ID'];
mysqli_query($con,"UPDATE Player SET 'rank' = $rangcounter WHERE ID='$updateid'");
$rangcounter++; //this variable should always be correctly high rank for any given loop. This way I can remove the highest ranked user (1st), then set every other one's rank to one less: the previously 2nd becomes the new 1st (when `$rangcounter` is 1); the previous 3rd will be the new 2nd (when `$rangcounter` is 2), and so on for every row.
}
header("redirect to main page");
exit();
?>
My idea was to create a new variable, which starts at 1, then, with every UPDATE I increment it. Because $result is ordered by the rank, it shouldn't be a problem, right? But it does not work, and I'm fairly sure it's because of a simple reason, but I just can't put my finger on it.
Could any of you help?
Update: TJ- solved it: MySQL update in a PHP While loop

Answer 1

Add quotes '' around $rangcounter in your mysqli_query.
mysqli_query($con,"UPDATE Player SET 'rank' = '$rangcounter' WHERE ID='$updateid'");
Hope this helps you

Answer 2

Change to
mysqli_query($con,"UPDATE Player SET rank = $rangcounter WHERE ID='$updateid'");
from
mysqli_query($con,"UPDATE Player SET 'rank' = $rangcounter WHERE ID='$updateid'");

Answer 3

From your explanation I understood that you could have
userId | rank
1 1
2 2
3 5
4 6
5 3
6 4
and after deleting user with with id=3 you want to have:
userId | rank
1 1
2 2
4 5
5 3
6 4
If the above is correct then all what you need is to excute after deleting the user
UPDATE Player SET rank = rank-1 WHERE rank > $theDeletedsRank

Answer 4

should not use single quotation '' for column names. Also always use php variables outside of query string like below.
Please try this.
mysqli_query($con,"UPDATE Player SET rank=".$rangcounter." WHERE ID=".$updateid."");
Hope this works fine.