function projekod_add_to_queue()
{
    global $wpdb;
    if (isset($_POST) && $_POST) {
        $customers = projekod_get_all_customers();
        foreach ($_POST['ids'] as $id) {
            foreach ($customers as $customer) {
                if ($customer->id == $id) {
                    $argument = ['ad' => $customer->first_name, 'soyad' => $customer->last_name];
                    $wpdb->insert($wpdb->prefix . 'sms_queue', ['date_added' => date('Y-m-d H:i:s'), 'status' => '1', 'sms_content' => null, 'template_id' => $_POST['sms_id'], 'phone_number' => $customer->telephone, 'arguments' => json_encode($argument)]);
                }
            }
        }
    }
}
<?php

require __DIR__ . '/head.php';
$customers = projekod_get_all_customers();
$sms = projekod_get_sms_template_from_status(1);
projekod_add_to_queue();
?>

<div style="margin:20px;">
    <form method="post" action="">
        <h4>Kullanıcı seçimi yapınız</h4>
        <table class="wp-list-table widefat fixed striped">
            <thead>
            <tr>
                <th class="manage-column column-cb check-column"><input type="checkbox"></th>
                <th>Ad Soyad</th>
                <th>Mail Adresi</th>
                <th>GSM</th>
                <th>İlk Sipariş Tarihi</th>
            </tr>
            </thead>
            <tbody>
            <?php 
if (is_array($customers)) {
    ?>
                <?php 
    foreach ($customers as $customer) {
        ?>
                <tr class="manage-column column-cb check-column">
                    <td><input type="checkbox" name="ids[]" value="<?php 
        echo $customer->id;