连接失败：SQLSTATE [42000]：语法错误或访问冲突：1064

Posted 2021-04-05

我已经看到很多类似于我的问题，但是我的不一样：我的错误不是因为在SQL中使用"keyword"引起的！

当我运行我的代码，如果我取消WHERE子句或我使用硬编码值，如" WHERE customerNumber = 356"它工作正常，但如果我尝试使用变量$custom_n的值，它会抛出一个错误。

<?php 
            $custom_n = $_POST["emp"];
            $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 phone, salesRepEmployeeNumber, creditLimit FROM customers WHERE customerNumber = $custom_n");
                $stmt -> execute();
                $result = $stmt->setFetchMode(PDO::FETCH_ASSOC); 
                foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v) { 
                    echo $v;
                }
            }
            catch(PDOException $e) {
                echo "Connection failed: " . $e->getMessage();
            }

            $conn = null;

        ?>

如果我对custom_n和gettype做一个回音我得到：353字符串这是我想要的。

这是完整的错误：

连接失败：SQLSTATE [42000]：语法错误或访问冲突：1064 SQL语法中有错误;检查与您的MariaDB服务器版本对应的手册，以便在第1行的''附近使用正确的语法

正如Magnus Eriksson所建议的，如果我做一个var_dump($custom_n);我得到这个输出：string(12) ""

答案

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

你的代码看起来很好，所以我假设你的字符串转义查询。下次尝试使用预备语句。

另一答案

正如Magnus Eriksson所建议的那样，我的POST方法存在问题......即使它似乎没问题，我的变量custom_n也有一个奇怪的var_dump输出string(12)""。我记得我以前使用过相同的代码而且工作正常，所以我只是修改代码完全相同：在我有发送“POST变量”的表单的页面中，我使用了这段代码：

<?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;

        ?>

我以为我可以节省一些时间从另一个查询获取custom_n，我在该页面中填充表而不是进行另一个查询。我不确定这有什么问题，但随着这种变化，我解决了这个问题：

<?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;

        ?>

我要感谢大家，特别是MagnusEriksson，MasivuyeCokile和Pr1nc3，而我对参数化的准备语句一无所知。非常感谢，如果你发现为什么以前的代码不起作用，请随时评论：D。

另一答案

首选方式是绑定。你可以像这样绑定param。你可以参考here

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

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