MySQL Calculate Percentage of Total Donations - php

Question

I have a donation site and a little bit stuck on finding what percent of the Donation Goal that the Current Donations are at?
In my MySQLi database I have two columns - donation_goal (numerical eg. 500) and current_raised (numerical eg. 20.00).
What I need to do is find and display how much in percentage has been raised currently out of the donation goal. So if £10 was donated and the goal was £100 it would display 10%. But it would do this each time the page was loaded.
I display each page with the code below and need to find a way to add this feature to this code below:
<?php
$sql = "SELECT * FROM pages ORDER BY RAND() LIMIT 3";
$result = mysqli_query($mysqli,$sql)or die(mysqli_error());
while($row = mysqli_fetch_array($result)) {
$page_name = $row['page_name'];
$count = strlen($page_name);
if($count < 27){
$space = '<br> <br/>';
} else {
$space = '';
}
$page_dp = $row['page_dp'];
$donation_goal = $row['donation_goal'];
$current_raised = $row['current_raised'];
?>
<div class="col-sm-6 col-md-4">
<div class="thumbnail">
<img src="pageimg/<? echo $page_dp; ?>" style="width:348px;height:233px;" alt="Page Image">
<div class="caption">
<h3><? echo $page_name; ?> <? echo $space; ?></h3>
<div class="progress">
<div class="progress-bar progress-bar-success progress-bar-striped" role="progressbar" aria-valuenow="10" aria-valuemin="0" aria-valuemax="100" style="width: 10%">10%
<span class="sr-only">10% Complete (success)</span>
</div>
</div>
<p><b>£<? echo $donation_goal; ?>.00</b> Target | <b>£<? echo $current_raised; ?></b> Raised</p>
Here is a little info about this current topic, please help us raise more than we can! We need your help!
<p>Donate Now Details</p>
</div>
</div>
</div>
<?
}
?>
I have tried adding this code to the mix, but receiving errors so am pretty sure I have no idea how to add it correctly:
$sql = "SELECT * FROM pages, COUNT( current_raised ) AS test, concat(round(( current_raised/donation_goal * 100 ),2),'%') AS percentage ORDER BY id DESC LIMIT 3";
This just gave out errors. Any ideas of how to do this efficiently with short code?

Answer 1

If you would like to calculate the percentage of the dontation from the goal you could do this directly in your query:
SELECT page_dp,
donation_goal,
current_raised,
ROUND(current_raised/donation_goal*100) percentage
FROM pages
ORDER BY RAND()
LIMIT 3
Then you only need to output the percentage within your loop:
<span class="sr-only"><?php print $row['percentage']; ?>% Complete (success)</span>

Answer 2

Is this what you want?
SELECT p.*, pc.cr / donation_goal
FROM pages p CROSS JOIN
(SELECT SUM(current_raised) as cr FROM pages) pc
ORDER BY RAND()
LIMIT 3;