What are the potential security risks associated with allowing user input in SQL queries in PHP?

Allowing user input in SQL queries in PHP can lead to SQL injection attacks, where malicious users can manipulate the input to execute unauthorized SQL commands. To prevent this, it is crucial to sanitize and validate user input before incorporating it into SQL queries. One way to do this is by using prepared statements with parameterized queries, which separate the SQL code from the user input, thus preventing SQL injection attacks. 

// Establish a database connection
$pdo = new PDO("mysql:host=localhost;dbname=mydatabase", "username", "password");

// Prepare a SQL statement with a parameterized query
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");

// Bind the user input to the parameter
$stmt->bindParam(':username', $_POST['username']);

// Execute the query
$stmt->execute();

// Fetch the results
$results = $stmt->fetchAll(PDO::FETCH_ASSOC);

Keywords

SQL injection user input validation prepared statements PDO security vulnerabilities

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