正如magnus eriksson所建议的，我的post方法有问题。。。即使看起来没问题，我的变量custom有一个奇怪的var\u dump输出 string(12)"" . 我记得我以前使用过相同的代码并且正在工作，所以我只需将代码修改为完全相同：在我有发送“post变量”的表单的页面中，我使用了以下代码：

<?php 

            $servername = "localhost";
            $username = "root";
            $password = "";

            $custom_n = array();

            try {
                $conn = new PDO("mysql:host=$servername;dbname=classicmodels", $username, $password);
                $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

                $stmt = $conn -> prepare("SELECT checkNumber, paymentDate, amount, customerNumber FROM payments ORDER BY paymentDate DESC");
                $stmt -> execute();
                $result = $stmt->setFetchMode(PDO::FETCH_ASSOC); 
                foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v) { 
                    echo $v;
                    if ($k == 'customerNumber') {
                        array_push($custom_n, $v);
                    }
                }

                $tableCodes = "<table id='buttons'>";
                foreach ($custom_n as $c) {
                    $tableCodes .= "
                        <tr>
                            <td>
                                <form action='customers.php' method='post' target='POPUPW' onsubmit=\"POPUPW = window.open('about:blank','POPUPW', 'width=800px,height=600px');\">
                                    <button type='submit' name='code' value='$c'>Details</button>
                                </form>
                            </td>
                        </tr>
                    ";
                }
                $tableCodes .= "</table>";
                echo $tableCodes;
            }
            catch(PDOException $e) {
                echo "Connection failed: " . $e->getMessage();
            }

            $conn = null;

        ?>

我想我可以腾出一些时间从另一个查询中获取自定义值，这样就可以填充该页中的表，而不是进行另一个查询。我不确定这有什么问题，但通过这种改变，我解决了问题：

<?php 

            $servername = "localhost";
            $username = "root";
            $password = "";

            try {
                $conn = new PDO("mysql:host=$servername;dbname=classicmodels", $username, $password);
                $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

                $stmt = $conn -> prepare("SELECT checkNumber, paymentDate, amount, customerNumber FROM payments ORDER BY paymentDate DESC");
                $stmt -> execute();
                $result = $stmt->setFetchMode(PDO::FETCH_ASSOC); 
                foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v) { 
                    echo $v; 
                }

                $customQuery = $conn -> prepare("SELECT customerNumber FROM payments ORDER BY paymentDate DESC");
                $customQuery -> execute();
                $custom = $customQuery->fetchAll(PDO::FETCH_COLUMN);
                $tableCodes = "<table id='buttons'>";
                foreach ($custom as $c) {
                    $tableCodes .= "
                        <tr>
                            <td>
                                <form action='customers.php' method='post' target='POPUPW' onsubmit=\"POPUPW = window.open('about:blank','POPUPW', 'width=800px,height=600px');\">
                                    <button type='submit' name='emp' value='$c'>Details</button>
                                </form>
                            </td>
                        </tr>
                    ";
                }
                $tableCodes .= "</table>";
                echo $tableCodes;
            }
            catch(PDOException $e) {
                echo "Connection failed: " . $e->getMessage();
            }

            $conn = null;

        ?>

我必须感谢每一个人，特别是magnuseriksson，masivuyecokile和pr1nc3，他们是我所不知道的关于参数化准备语句的人。非常感谢您，如果您发现以前的代码不起作用的原因，请随时发表评论：d。

首选方式是绑定。你可以这样和param绑定。你可以参考这里

$stmt = $conn -> prepare("SELECT phone, salesRepEmployeeNumber, creditLimit FROM customers WHERE customerNumber = :customernumber");

$stmt->bindParam(':customernumber', $custom_n, PDO::PARAM_INT);

$stmt = $conn -> prepare("SELECT phone, salesRepEmployeeNumber, creditLimit FROM customers WHERE customerNumber = ?");
$stmt->execute(array($custom_n));

你的代码看起来不错，所以我假设你的字符串逃逸了查询。下次尽量使用事先准备好的语句。