致命错误：未捕获的 PDOException：SQLSTATE[42000] 语法错误或访问冲突

Question

我正在实现一个简单的代码来检查一封电子邮件是否已经在我的数据库中，以及它是否正在从数据库中删除它。但是，我收到此错误消息：

Fatal error: Uncaught PDOException: SQLSTATE[42000]: Syntax error or access
violation: 1064 You have an error in your SQL syntax; check the manual that 
corresponds to your MySQL server version for the right syntax to use near 
'@gmail.com' at line 1 in /home/saintpao/public_html/deleteNewsletter.php:24 Stack 
trace: #0 /home/saintpao/public_html/deleteNewsletter.php(24): 
PDOStatement->execute() #1 {main} thrown in /home/saintpao/public_html
/deleteNewsletter.php on line 24

这是conectar.php 文件

$dbhost = "myHost";
$dbuser = "myUser";
$dbpass = "myPassword";
$dbname = "myDBName";
try {
    $db = new PDO("mysql:host=$dbhost;dbname=$dbname", $dbuser, $dbpass,  
                  array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES 'UTF8'"));
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}catch(Exception $error) {
    die("Error conexión BBDD " . $error->getMessage());
}   

这是deleteNewsletter.php 文件：

function sanitazeEmail($email){
   if(empty($email)){
       return "";
   }
   $sanitized = filter_var($email, FILTER_SANITIZE_EMAIL);
   if(filter_var($sanitized, FILTER_VALIDATE_EMAIL)){
       return $sanitized;
   }
   return "";
}

$success = false;
$email = sanitazeEmail($_POST['email']);

if(!empty($email)){
    require_once 'conectar.php';

    $sql = "SELECT `email` FROM `emails` WHERE `email` = " . $email;
    $statement = $db->prepare($sql);

    if($statement->execute()){
        $sql_delete = "DELETE FROM `emails` WHERE `email` =" . $email;
        $statement = $db->prepare($sql_delete);
        $success = $statement->execute();
    }
}

与数据库的连接有效，因为我可以在其他文件中进行 SELECT 请求，所以deleteNewsletter.php 文件肯定有问题。知道有什么问题吗？

Answer 1

您的错误是电子邮件是一个字符串，应该被引用。但是，您使用的是 PDO，您可以使用准备好的语句来避免此类错误：

$sql_delete = "DELETE FROM `emails` WHERE `email` = :email";
$statement = $db->prepare($sql_delete);
$sucess = $statement->execute([':email' => $email]);

请注意，您的select 查询并不是真正有用，您可以只执行delete 查询。请注意，$statement->execute() 返回的是语句，而不是结果。

正如@NigelRen 指出的那样，您可以使用$statement->rowCount() 来检查是否删除了一行。