Look! There is a trap with PDOStatement::bindParam!-PHP Tutorial-php.cn

Home

Backend Development

PHP Tutorial

Look! There is a trap with PDOStatement::bindParam!

藏色散人

Nov 20, 2020 pm 03:35 PM

Recommended: "PHP Video Tutorial"

Without further ado, let’s look at the code directly:

<?php
$dbh = new PDO(&#39;mysql:host=localhost;dbname=test&#39;, "test");
$query = <<<query
  INSERT INTO `user` (`username`, `password`) VALUES (:username, :password);
QUERY;
$statement = $dbh->prepare($query);
$bind_params = array(&#39;:username&#39; => "laruence", &#39;:password&#39; => "weibo");
foreach( $bind_params as $key => $value ){
    $statement->bindParam($key, $value);
}
$statement->execute();

Excuse me, what is the final SQL statement executed above? Is there any problem with the code?

Okey, I think most students will think that the final SQL executed is:

INSERT INTO `user` (`username`, `password`) VALUES ("laruence", "weibo");

But, unfortunately, you are wrong, the final SQL executed is :

INSERT INTO `user` (`username`, `password`) VALUES ("weibo", "weibo");

Is it a big trap?

------If you want to find the reason yourself, then don’t continue reading------ ---

This problem comes from a bug report today: #63281

The reason is that the difference between bindParam and bindValue is that bindParam requires the second parameter to be a reference Variable (reference).

Let us disassemble the foreach of the above code, that is, this foreach:

<?php
foreach( $bind_params as $key => $value ){
    $statement->bindParam($key, $value);
}

is equivalent to:

<?php
//第一次循环
$value = $bind_params[":username"];
$statement->bindParam(":username", &$value); //此时, :username是对$value变量的引用
//第二次循环
$value = $bind_params[":password"]; //oops! $value被覆盖成了:password的值
$statement->bindParam(":password", &$value);

So, when using bindParam When using it, you should pay special attention to this trap when used in conjunction with foreach. So what is the correct approach?

1. Do not use foreach, but assign values manually

<?php
$statement->bindParam(":username", $bind_params[":username"]); //$value是引用变量了
$statement->bindParam(":password", $bind_params[":password"]);

2. Use bindValue instead of bindParam, or Pass the entire parameter array directly in execute.

3. Use foreach and reference (not recommended, see: Weibo for the reason)

<?php
foreach( $bind_params as $key => &$value ) { //注意这里
    $statement->bindParam($key, $value);
}

Finally, expand on the requirement that parameters be references, And there are functions with lag processing, so be careful when using foreach!

Original address: https://www.laruence.com/2012/10/16/2831.html

The above is the detailed content of Look! There is a trap with PDOStatement::bindParam!. For more information, please follow other related articles on the PHP Chinese website!

Statement

This article is reproduced at:laruence. If there is any infringement, please contact admin@php.cn delete

PHP's Purpose: Building Dynamic WebsitesApr 15, 2025 am 12:18 AM

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP: Handling Databases and Server-Side LogicApr 15, 2025 am 12:15 AM

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

How do you prevent SQL Injection in PHP? (Prepared statements, PDO)Apr 15, 2025 am 12:15 AM

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python: Code Examples and ComparisonApr 15, 2025 am 12:07 AM

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP in Action: Real-World Examples and ApplicationsApr 14, 2025 am 12:19 AM

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP: Creating Interactive Web Content with EaseApr 14, 2025 am 12:15 AM

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python: Comparing Two Popular Programming LanguagesApr 14, 2025 am 12:13 AM

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

The Enduring Relevance of PHP: Is It Still Alive?Apr 14, 2025 am 12:12 AM

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.

See all articles