Print calculated Value of variable before its been calculated - php

Question

This is a tricky question to search, hence my post here. I have a a header that displays the sum of all the values in a column of a table that is printed below it. However the table is generated from a MYSQL table and the sum of the column values is calculated as it is generated. So somehow I have to have a variable printed but only after the table is generated and I am not sure how to pass the variables back up to the print statement so it doesn't always print out a 0
I feel like the solution is that the sum should call a script (Javascipt) that generates and prints the table returning the sum of columns to then be printed. But I am not sure how I would do this
echo "
<h3>EPL</h3>
<h5>Total Score: $total</h5>
<table class='table table-bordered'>
<tr>
<th>#</th>
<th>Name</th>
<th>Score</th>
</tr>
<tbody class='row_position'>"?>
<?php
require('db_config.php');
$tablename = $_SESSION['username'] . "_epl";
$_SESSION['tablename'] = $tablename;
$sql = "SELECT * FROM $tablename ORDER BY position_order";
$users = $mysqli->query($sql);
while($user = $users->fetch_assoc()){
$con = mysqli_connect('localhost', 'root', 'root', 'predictions');
$sql1 = "SELECT * FROM `predictions`.`".$tablename."` WHERE (CONVERT(`title` USING utf8) LIKE '%".$user['title']."%')";
$sql2 = "SELECT * FROM `predictions`.`epl` WHERE (CONVERT(`title` USING utf8) LIKE '%".$user['title']."%')";
$result = mysqli_query($con, $sql1);
$row = $result->fetch_assoc();
$position1 = $row['position_order'];
$result->close();
$result = mysqli_query($con, $sql2);
$row = $result->fetch_assoc();
$position2 = $row['position_order'];
$total += abs($position1-$position2);
?>
<tr id="<?php echo $user['id'] ?>">
<td><?php echo $user['position_order'] ?></td>
<td><?php echo $user['title'] ?></td>
<td><?php echo abs($position1-$position2); ?></td>
</tr>
<?php } ?>
</tbody>
</table>
To explain the table further, each user has their own table with the same format username_league, so I use some php code to grab the table. Additionally I have a base case table in this case 'epl' in which I compare the tables and calculate the scores based on the absolute difference in the column 'position_order'.

Answer 1

You should always aim for separation of your code and presentation. And beyond that, your database code is extremely inefficient. You're re-creating an entire database object for every instance of your original query.
Just put your PHP code before the HTML, or better yet in a separate file.
<?php
$total = 0;
require('db_config.php');
$tablename = $_SESSION['username'] . "_epl";
$_SESSION['tablename'] = $tablename;
$sql = "SELECT id, position_order, title FROM `$tablename` ORDER BY position_order";
$users_result = $mysqli->query($sql);
while($user = $users_result->fetch_assoc()) {
$users[] = $user;
}
foreach ($users as $user) {
$sql1 = "
SELECT position_order FROM `$tablename` WHERE CONVERT(`title` USING utf8) LIKE '%$user[title]%' LIMIT 1
UNION
SELECT position_order FROM `epl` WHERE CONVERT(`title` USING utf8) LIKE '%$user[title]%' LIMIT 1
";
$result = $mysqli->query($sql1);
$row = $result->fetch_assoc();
$position1 = $row['position_order'];
$user["position1"] = $position1;
$row = $result->fetch_assoc();
$position2 = $row['position_order'];
$user["position2"] = $position2;
$total += abs($position1 - $position2);
}
?>
There you are; using a single database object, one third fewer queries, all your values in an array. They're ready to use later in the file, or in your separate HTML view:
<h3>EPL</h3>
<h5>Total Score: <?=$total?></h5>
<table class='table table-bordered'>
<tr>
<th>#</th>
<th>Name</th>
<th>Score</th>
</tr>
<tbody class='row_position'>
<?php foreach($users as $user):?>
<tr id="<?=$user['id'] ?>">
<td><?=$user['position_order'] ?></td>
<td><?=$user['title'] ?></td>
<td><?=abs($user["position1"]-$user["position2"]); ?></td>
</tr>
<?php endforeach; ?>
</tbody>
</table>
I don't know enough about the structure here, but I'd be very surprised if you couldn't make this a single database query.

Answer 2

Output buffering is your friend! Simply call ob_start before outputting the table i.e.
ob_start();
echo "
<table class='table table-bordered'>
<tr>
<th>#</th>
<th>Name</th>
<th>Score</th>
</tr>
<tbody class='row_position'>"?>
...
then once you have done generating the table, you can collect the output of the table's content using ob_get_clean, output the header and then the table content:
...
$table = ob_get_clean();
echo "<h3>EPL</h3>
<h5>Total Score: $total</h5>";
echo $table;