PHP old data still showing after POST - php

Question

The code below works, in that, it updates the database correctly. However, after the post is completed the data on the page is old i.e. $reader_busy[0] is not updated even though it is driven by a SELECT query.
To force $reader_busy[0] to update properly on the users screen a refresh is required. This means the pages reloads after the post and then refreshes.
How do I get the page to display the correct data from the mysql without having to load the page twice?
Simplified version of my PHP code:
<?php
$reader_key = 'jm2';
$reader_busy_query = "SELECT `BusyWithClient` " .
"FROM {$wpdb->prefix}assistant " .
"WHERE `Key`='" . $reader_key . "'";
$reader_busy = $wpdb->get_col( $wpdb->prepare( $reader_busy_query ) );
$busy_with_client = $reader_busy[0];
if(isset($_POST['toggle'])){
$result = $wpdb->update(
$wpdb->prefix . 'assistant',
array('BusyWithClient' => $busy_with_client),
array('Key' => $reader_key)
);
// I want to remove / replace this line, and still see updated data.
echo "<meta http-equiv='refresh' content='0; url=" . curPageURL() . "#instructions" . "'>";
}
?>
<h1>
<?php print_r('busy: ' . $reader_busy[0]); ?>
<h1>
<form method="post" action="<?php echo curPageURL() . '#instructions'; ?>">
<input type="submit" name="toggle" value="toggle" >
</form>

Answer 1

Just flip the order of how you do things. Instead retrieving then updating, update before you retrieve.
<?php
if (isset($_POST['toggle'])) {
$result = $wpdb->update(
$wpdb->prefix . 'assistant',
array('BusyWithClient' => $busy_with_client),
array('Key' => $reader_key)
);
}
$reader_busy_query = "SELECT `BusyWithClient` " .
"FROM {$wpdb->prefix}assistant " .
"WHERE `Key`='" . $reader_key . "'";
$reader_busy = $wpdb->get_col($wpdb->prepare($reader_busy_query));
?>

Answer 2

I see what you are trying to accomplish and that's looks impossible. Instead of refreshing page you can (should) make ajax request and update your page by refreshing only the page data that you need.
EDIT:
Because, you are trying to post to a page with ANCHOR, and browsers by there nature will try to find information on the page without refreshing it. Browser still sends information to post, so it updates in background, but not refreshes the page.
You should make post over ajax request and return data to field, or post it to another php file (without #hashtag).
PS - You will not get more answerers if you will downgrade every answers that didn't work for you :)