matching between sql column and texfield input using php - php

Question

im trying to match my textfield input of a "coupon_code" to a value in a sql table. i have three files that connect to each other. also, there should be an alert if the texfield matches.
HTML: (membership.php)
<?php
session_start();
require_once('membership.vc.php');
?>
<form>
<div class="form-row">
<div class="col col-md-8">
<input type="text" class="form-control" aria-describedby="sizing-addon1" name="promocode3" placeholder="ENTER PROMO CODE">
</div>
<div class="col col-md-4">
<input type="submit" class="btn color-white mwc-orange-background-color" name="redeem" value="REDEEM">
</div>
</div>
</form>
PHP: (membership.vc.php)
<?php
require_once($routePath . "_mc/PromoCode.mc.php");
$mcPromoCode = new PromoCode_MC();
if (isset($_POST['redeem']) && $_POST['redeem'] == 'REDEEM'){
$pcode3_txtfield = $_POST['promocode3'];
$rowpcode3 = $mcPromoCode->SelectPromoCode3($db, $p3id);
$pcode3 = $rowpcode3['coupon_code'];
if ($pcode3_txtfield == $pcode3 ){
echo "<script>
alert('There are no fields to generate a report');
window.location.href='admin/ahm/panel';
</script>";
}
}
?>
SQL Function: (PromoCode.mc.php)
<?php Class PromoCode_MC {
public function SelectPromoCode3($db, $p3id) {
$stmt = $db->prepare(
" SELECT *
FROM mywhitecard.promocode_3
WHERE p3id = :p3id ");
$stmt->bindValue(':p3id', $p3id, PDO::PARAM_INT);
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_ASSOC);
return $row; } } ?>
$pcode3 should get the column and $pcode3_txtfield should get the textfield input, which part did i do wrong? since there is no alert popup.
UPDATE: tried to do what the comments said, i thought using the primary key of the table will work but still no effect
UPDATE: i tried:
<?php Class PromoCode_MC {
public function SelectPromoCode3($db, $pcode3_txtfield) {
$stmt = $db->prepare(
" SELECT *
FROM mywhitecard.promocode_3
WHERE pcode3_txtfield = :coupon_code ");
$stmt->bindValue(':pcode3_txtfield', $pcode3_txtfield, PDO::PARAM_INT);
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_ASSOC);
return $row; }
} ?>
no effect