It is not possible to output data from MySQL (Wordpress) - php

Question

I use a Wordpress site, I do my search on a custom database called "operations". The search is performed on the website.
I need to get other results from the table related to this row on request, not just what I entered. And get other data related to this string. Here is the search form on the site:
<form method="post" action="https://site-name.com/wp-content/themes/theme/select_user.php">
<label for="sku">SKU:</label><br/>
<input type="text" name="sku" size="30"><br/>
<label for="barcode">Barcode:</label><br/>
<input type="text" name="barcode" size="30"><br/>
<input id="submit" type="submit" value="Search"><br/>
</form>
</fieldset>
The database has the following columns: id, date, title, size, sku, barcode, price
File Contents select_user.php:
require( __DIR__ . '/../../../wp-load.php' );
global $wpdb;
$sku = trim($_REQUEST['sku']);
$barcode = trim($_REQUEST['barcode']);
$sql_select = $wpdb->get_results(
$wpdb->prepare(
"
SELECT * FROM " . $wpdb->prefix . "operations
WHERE sku='$sku' || barcode='$barcode',
ARRAY_N
"
)
);
if ($sql_select)
{
foreach($sql_select as $row)
{
echo 'SKU: ' . $row['sku'] .'</br>';
echo 'Barcode: ' . $row['barcode'] .'</br>';
}
}
else {
echo 'No results';
}
With this code, I get the answer "no results".
I would be grateful for any help

Answer 1

use the post hook for wp forms not directly use .php file
add_action( 'admin_post_add_foobar', 'prefix_admin_add_foobar' );
function prefix_admin_add_foobar() {
// Handle request then generate response using echo or leaving PHP and using HTML
}
for your form use :
<form action="http://www.example.com/wp-admin/admin-post.php" method="post">
<input type="hidden" name="action" value="add_foobar">
<input type="hidden" name="data" value="foobarid">
<input type="submit" value="Submit">
</form>

Answer 2

I created my own shortcode, and placed everything that is necessary there. Everything works.
function custom_search_func( $atts ){
echo '<fieldset>
<form action="' . get_permalink() . '" method="POST">
<label for="sku">SKU:</label><br/>
<input type="text" name="sku" size="30"><br/>
<label for="barcode">Barcode:</label><br/>
<input type="text" name="barcode" size="30"><br/>
<label for="date">Date:</label><br/>
<input type="date" name="date" size="30"><br/>
<input type="submit" value="Search">
</form>
</fieldset>';
global $wpdb;
$sku = trim($_REQUEST['sku']);
$barcode = trim($_REQUEST['barcode']);
$date = trim($_REQUEST['date']);
$sql_select = $wpdb->get_results(
$wpdb->prepare(
"
SELECT id, date, title, size, barcode, sku, price FROM " . $wpdb->prefix . "operations
WHERE sku='$sku' || barcode='$barcode' || date='$date'
"
)
);
if ($sql_select)
{
echo '<table border="1" width="100%" cellpadding="5">';
echo '<tr><th>ID</th>';
echo '<th>Title</th>';
echo '<th>Size</th>';
echo '<th>SKU</th>';
echo '<th>Barcode</th>';
echo '<th>Price</th>';
echo '<th>Date</th></tr>';
foreach ( $sql_select as $id) {
echo '<tr>';
echo '<td>';
echo $id->id;
echo '</td>';
echo '<td>';
echo $id->title;
echo '</td>';
echo '<td>';
echo $id->size;
echo '</td>';
echo '<td>';
echo $id->sku;
echo '</td>';
echo '<td>';
echo $id->barcode;
echo '</td>';
echo '<td>';
echo $id->price;
echo '</td>';
echo '<td>';
echo $id->date;
echo '</td>';
echo '</tr>';
}
echo '</table>';
}
else {
echo 'No results';
}
}
add_shortcode( 'customsearch', 'custom_search_func' );
Use the [customsearch] shortcode to output this anywhere on the page