Why is it important to validate user input and sanitize data in PHP scripts that interact with databases?

It is important to validate user input and sanitize data in PHP scripts that interact with databases to prevent SQL injection attacks, which can compromise the security of the database. By validating user input, you can ensure that only expected data is being processed, while sanitizing data helps to remove potentially harmful characters or code that could be used for malicious purposes. 

// Validate user input
$username = isset($_POST['username']) ? $_POST['username'] : '';
$password = isset($_POST['password']) ? $_POST['password'] : '';

// Sanitize data
$username = filter_var($username, FILTER_SANITIZE_STRING);
$password = filter_var($password, FILTER_SANITIZE_STRING);

// Use prepared statements to interact with the database
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username AND password = :password");
$stmt->bindParam(':username', $username);
$stmt->bindParam(':password', $password);
$stmt->execute();

Keywords

SQL injection XSS attacks prepared statements filter_var htmlentities

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