Не получается вывести данные из бд через кнопку поиск, в чем ошибка? я хочу чтобы выводились данные через поиск и их можно было бы удалить или отредактировать.
Вот примерно такой формы

<?php require_once "head.php"; ?>

<?php
$isAddClient    = isset($_GET['add_client']);
$isDeleteClient = isset($_GET['delete']);
$isU            = isset($_GET['u']);

if($isDeleteClient)
{
    $id = $_GET['delete'];
    
    $stmt = $DBH->prepare("DELETE FROM `clients_table` WHERE `id` = :id");
    $stmt->bindParam(":id", $id);
    $stmt->execute();
    
    header("location: index.php?page=clients");
}
else if($isAddClient)
{
    $fio        = $_GET["client_fio"];
    $phone      = $_GET["client_phone"];
    $carNumber  = $_GET["client_carNumber"];
    $passport   = $_GET["client_passport"];
    
    $stmt = $DBH->prepare("INSERT INTO `clients_table` VALUES(NULL, :fio, :phone, :carNumber, :passport)");
    $stmt->bindParam(":fio", $fio);
    $stmt->bindParam(":phone", $phone);
    $stmt->bindParam(":carNumber", $carNumber);
    $stmt->bindParam(":passport", $passport);
    $stmt->execute();
    
    header("location: index.php?page=clients");
}
else if($isU)
{
    $stmt = $DBH->prepare("UPDATE `clients_table` SET `fio` = :fio, `phone` = :phone, `carNumber` = :car, `passport` = :pass WHERE `id` = :id");
    $stmt->bindParam(":fio", $_GET['fio-1']);
    $stmt->bindParam(":phone", $_GET['phone-1']);
    $stmt->bindParam(":car", $_GET['car-1']);
    $stmt->bindParam(":pass", $_GET['pass-1']);
    $stmt->bindParam(":id", $_GET['id-1']);
    $stmt->execute();
    
    header('location: index.php?page=clients');
}

?>

<?php
if (isset($_POST['search_buttom'])) {
$car_number = $_POST['search_car_number'];
$stmt = $DBH->prepare("SELECT * FROM `clients_table` WHERE  `carNumber` = :car_number");
    $stmt->bindParam(":car_number", $car_number);
    $stmt->execute();
	echo '<form method="post">
  <input type="text" value="'.$car_number.'" required />
  <input type="submit" value="Добавить" />
</form>';
}
?>

<form method='POST' action='' name='search_form'>
<input type='text' name='search_car_number' value='' placeholder='Введите номер машины'> <input type='submit' name='search_buttom' value='Поиск'>
</form>


<div class="wrap1">
    <div class="table clients vopros">
        <div class="table-row">
            <div class="table-cell"> # </div>
            <div class="table-cell"> ФИО </div>
            <div class="table-cell"> Тел. номер </div>
            <div class="table-cell"> Номер машины </div>
            <div class="table-cell"> Паспортные данные </div>
            <div class="table-cell"> Действия </div>
        </div>
        <form class="table-row" action="index.php?page=clients" method="get">
            <div class="table-cell">  </div>
            <div class="table-cell"> <input type="text" name="client_fio" placeholder="Петров Петр Петрович" required="on" autocomplete="off"> </div>
            <div class="table-cell"> <input type="text" maxlength="11" onkeyup="this.value = this.value.replace (/[^\d]/g, '')" name="client_phone" placeholder="88005553535" required="on" autocomplete="off"> </div>
            <div class="table-cell"> <input type="text" name="client_carNumber" placeholder="о000оо" required="on" autocomplete="off"> </div>
            <div class="table-cell"> <input type="text" onkeyup="this.value = this.value.replace (/[^\d-]/g, '')" name="client_passport" placeholder="111-123123" required="on" autocomplete="off"> </div>
            <div class="table-cell"> <input type="submit" name="add_client" value="Добавить клиента"> </div>
            <input type="hidden" name="page" value="clients">
        </form>
        <?php
        $stmt = $DBH->prepare("SELECT * FROM `clients_table` ORDER BY `id` DESC");
        $stmt->execute();
        
        while($row = $stmt->fetch(PDO::FETCH_OBJ)):
        ?>
        <form class="table-row">
            <div class="table-cell"> <?= $row->id ?> </div>
            <div class="table-cell"> <input type="text" name="fio-1" value="<?= $row->fio ?>" required> </div>
            <div class="table-cell"> <input type="text" maxlength="11" onkeyup="this.value = this.value.replace (/[^\d]/g, '')" name="phone-1" value="<?= $row->phone ?>" required> </div>
            <div class="table-cell"> <input type="text" name="car-1" value="<?= $row->carNumber ?>" required> </div>
            <div class="table-cell"> <input type="text" onkeyup="this.value = this.value.replace (/[^\d-]/g, '')" name="pass-1" value="<?= $row->passport ?>" required> </div>
            <div class="table-cell"> <a class="silka" href="?page=clients&delete=<?= $row->id ?>"> Удалить </a> <input type="submit" name="u" value="Изменить"></div>
            <input type="hidden" name="page" value="clients">
            <input type="hidden" name="id-1" value="<?= $row->id ?>">
        </form>
        <?php endwhile; ?>
    </div>
</div>