Mysql 绑定：元素数量不匹配

Question

我无法理解这条指令哪里出了问题。我不断收到元素数量与绑定值不匹配的警告。我正在尝试验证国家/地区的字段，用户可以在其中 select 他们注册的国家/地区，但是每当我运行在 xampp 上进行测试时，我都会收到警告，而信息却不是发送到数据库。

我不确定我的代码是否容易受到 sql 注入，因为我是 php 和 mysql 的新手。如果我删除国家/地区功能，表格将正常工作。我认为错误来自 html 表单，所以我不想在这里上传它。

这是 php 代码。

<?php
// Include config file
require_once "db.php";
 
// Define variables and initialize with empty values
$username = $password = $confirm_password = $country = "";
$username_err = $password_err = $confirm_password_err = $country_err = "";
 
// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){
 
    // Validate username
    if(empty(trim($_POST["username"]))){
        $username_err = "Please enter a username.";
    } else{
        // Prepare a select statement
        $sql = "SELECT id FROM users WHERE username = ?";
        
        if($stmt = mysqli_prepare($db, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_username);
            
            // Set parameters
            $param_username = trim($_POST["username"]);
            
            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                /* store result */
                mysqli_stmt_store_result($stmt);
                
                if(mysqli_stmt_num_rows($stmt) == 1){
                    $username_err = "This username is already taken.";
                } else{
                    $username = trim($_POST["username"]);
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }

            // Close statement
            mysqli_stmt_close($stmt);
        }
    }
    
    // Validate password
    if(empty(trim($_POST["password"]))){
        $password_err = "Please enter a password.";     
    } elseif(strlen(trim($_POST["password"])) < 6){
        $password_err = "Password must have atleast 6 characters.";
    } else{
        $password = trim($_POST["password"]);
    }
    
    // Validate confirm password
    if(empty(trim($_POST["confirm_password"]))){
        $confirm_password_err = "Please confirm password.";     
    } else{
        $confirm_password = trim($_POST["confirm_password"]);
        if(empty($password_err) && ($password != $confirm_password)){
            $confirm_password_err = "Password did not match.";
        }
    }
    

      // Validate Country
    if(empty(trim($_POST["country"]))){
        $country_err = "Please Choose a Country.";     
    } 
         else{
        $country = trim($_POST["country"]);
    }



    // Check input errors before inserting in database
    if(empty($username_err) && empty($password_err) && empty($confirm_password_err)){
        
        // Prepare an insert statement
        $sql = "INSERT INTO users (username, password, country) VALUES (?, ?, ?)";
         
        if($stmt = mysqli_prepare($db, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "ss", $param_username, $param_password, $param_country);
            
            // Set parameters
            $param_country = $country;
            $param_username = $username;
            $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash
            
            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Redirect to login page
                header("location: login.php");
            } else{
                echo "Something went wrong. Please try again later.";
            }

            // Close statement
            mysqli_stmt_close($stmt);
        }
    }
    
    // Close connection
    mysqli_close($db);
}
?>.`

Answer 1

我可以看到几件事：

您的输入错误检查不会检查“country_err”是否为空。
您的 mysqli_stmt_bind_param 仅定义了 2 个字段“ss”的类型，但您传入了 3 个字段，因此它应该是“sss”

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