Php Paypal通过数据库查询“立即购买”

为了在单击“立即购买”按钮时动态确定要使用的paypal卖家电子邮件地址，我想使用基于选择选项下拉框中的选择的sql查询来检索paypal电子邮件地址

有人知道这是否可以做到吗？这是我到目前为止的代码，但它没有捕获值

public function getForm($project_list, $business){  
?>
    <div id="payment_booking_main">            
        <!-- <form name="_xclick" id="payment_booking_form" action="https://www.paypal.com/cgi-bin/webscr" method="post"> -->
         <form name="_xclick" id="payment_booking_form" action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
            <input type="hidden" name="cmd" value="_xclick" /> 
            <input type="hidden" name="hosted_button_id" value="7ACEDNW8URDK2" /> 

            <!-- <input type="hidden" name="business" value="myemailaddress@website.info" /> -->

            <!-- try to populate business field for paypal e-mail address -->
            <input type="hidden" name="business" value="
                <?php
                    global $wpdb;
                    $paymentProject = $_POST['payment_booking_project'];
                    $result = $wpdb->get_results("SELECT project_paypal_address FROM {$wpdb->prefix}payment_booking_project WHERE project_name='{$paymentProject}'");

                    echo $result->project_paypal_address;
                ?>" />

            <input type="hidden" name="a3" value="1">
            <input type="hidden" name="p3" value="1">
            <input type="hidden" name="t3" value="D">
            <input type="hidden" name="no_note" value="1">
            <input type="hidden" name="currency_code" value="GBP">
            <input type="hidden" id="payment_booking_return_url" name="return" value="" />
            <input type="hidden" id="payment_booking_notify_url" name="notify_url" value="">
            <input type="hidden" id="payment_booking_total_amount" name="amount" value="0">
            <input type="hidden" id="payment_booking_item_name" name="item_name" value="">
            <input type="hidden" id="payment_booking_item_number" name="item_number" value="">

编辑：

为了提供更多的上下文，当这个表单加载时，它会填充来自数据库的输入。我想使用部分结果来查找电子邮件地址。该PHP如下所示：

<div id="payment_booking_project_selectform">
    <div class="payment_booking_line" style="heigth:20px !important;">
        <span class="payment_booking_label">Project :</span>
        <select id="payment_booking_project" name="payment_booking_project">
            <?php
                global $wpdb;
                $sql = "SELECT * FROM `{$wpdb->prefix}payment_booking_project` WHERE project_status =1";
                $project_list = $wpdb->get_results($sql);
                foreach($project_list as $project){
                    echo '<option value="'.$project->id.'" amount="'.number_format($project->project_amount, 2).'" description="'.$project->project_description.'" price="'.$project->project_price.'">'.$project->project_name.'</option>';
                    }
             ?>
         </select>
         <span id="payment_booking_project_description" style="font-size:12px;"></span>
     </div>

---

请确认您的查询是否根据需要选择电子邮件地址？要确认，请从输入字段中删除type=hidden，或在填充到隐藏的输入字段echo$result->project\u paypal\u address；？之前回显查询结果一次