What are the Risks of using mysql_* Functions in PHP?

MySQL functions in PHP, often referred to as mysql_* functions, have been a popular choice for developers to interact with MySQL databases. Did you say “NOT ANYMORE!“?

So now it’s essential to weigh the pros and cons of mysql_* functions in PHP to determine whether they are a good or bad choice for your PHP projects. This discussion will help you determine if you should use mysql_* functions in PHP or not.

Why you should use mysql_* functions in PHP?

1. Simplicity and Familiarity

One of the primary reasons developers have used mysql_* functions is their simplicity and familiarity. These functions offer an uncomplicated way to connect to and interact with MySQL databases. Let’s take a look at a basic example:

PHP

<?php
   // Using mysql_* functions to connect and query the database
  $conn = mysql_connect("localhost", "username", "password");
  mysql_select_db("database", $conn);
  $result = mysql_query("SELECT * FROM users");

?>

Output

Fatal error: Uncaught Error: Call to undefined function mysql_connect() in /home/guest/sandbox/Solution.php:3
Stack trace:
#0 {main}
  thrown in /home/guest/sandbox/Solution.php on line 3

For developers who are new to PHP and MySQL, the straightforward nature of mysql_* functions can be appealing, as it allows them to quickly get started with database interactions.

2. Legacy Code Support

If you’re maintaining older PHP applications that use mysql_* functions, they may still work correctly. In such cases, rewriting the code to use modern database libraries might not be a priority, especially if the codebase is small and isolated.

What are the Risks of using mysql_* Functions in PHP?

1. Deprecated Functions (Most important)

Perhaps the most significant issue with mysql_* functions is that they are deprecated and have been removed from recent versions of PHP, starting with PHP 7. Deprecated features can cause compatibility problems and expose your application to potential security vulnerabilities. It’s essential to keep your PHP codebase up to date with the latest standards and best practices.

2. Security Vulnerabilities

mysql_* functions lack support for modern security practices, such as prepared statements and parameterized queries. This makes your code susceptible to SQL injection attacks, one of the most common and dangerous security vulnerabilities. Here’s an example illustrating the vulnerability:

PHP

<?php
  // Using mysql_* functions without proper input validation
  $unsafeInput = $_POST['user_input'];
  $query = "SELECT * FROM users WHERE username = '$unsafeInput'";
  $result = mysql_query($query);
?>

Output

Fatal error: Uncaught Error: Call to undefined function mysql_query() in /home/guest/sandbox/Solution.php:5
Stack trace:
#0 {main}
  thrown in /home/guest/sandbox/Solution.php on line 5

In this example, a malicious user can manipulate the input to perform an SQL injection attack. To address this, you should switch to a library that supports prepared statements:

PHP

<?php
  // Using MySQLi with prepared statements for security
  $mysqli = new mysqli("localhost", "username", "password", "database");
  $unsafeInput = $_POST['user_input'];
  $query = "SELECT * FROM users WHERE username = ?";
  $stmt = $mysqli->prepare($query);
  $stmt->bind_param("s", $unsafeInput);
  $stmt->execute();
?>

3. Lack of Features

mysql_* functions lack many features and capabilities provided by more recent database extension libraries, such as MySQLi and PDO. These newer libraries offer features like object-oriented interfaces, support for multiple database backends, and enhanced functionality, making them more versatile and powerful.

4. Performance and Error Handling

Older mysql_* functions may not be as efficient as newer database libraries like MySQLi or PDO. Additionally, these libraries offer better error handling mechanisms, making it easier to diagnose and debug database-related issues in your code.

Conclusion

In the debate over whether mysql_* functions in PHP are good or bad, the verdict leans towards them being a less favorable choice. While they offer simplicity and familiarity, the fact that they are deprecated, lack security features, and fall short in terms of features, performance, and error handling makes them less suitable for modern PHP applications.

To ensure the security and maintainability of your PHP projects, it is advisable to transition to more modern database libraries like MySQLi or PDO. Making this shift, along with implementing prepared statements and parameterized queries, can help protect your applications from security vulnerabilities and leverage the advantages of contemporary database interaction tools.