What are the recommended steps for validating user input and sanitizing data to prevent SQL injection attacks in PHP scripts like the one discussed in the forum thread?

To prevent SQL injection attacks in PHP scripts, it is essential to validate user input and sanitize data before using it in SQL queries. This can be done by using prepared statements with parameterized queries or by using functions like mysqli_real_escape_string() to escape special characters. 

// Validate and sanitize user input to prevent SQL injection
$username = $_POST['username'];
$password = $_POST['password'];

// Using prepared statements with parameterized queries
$stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->bind_param("ss", $username, $password);
$stmt->execute();
$result = $stmt->get_result();

// Alternatively, sanitize input using mysqli_real_escape_string
$username = mysqli_real_escape_string($mysqli, $_POST['username']);
$password = mysqli_real_escape_string($mysqli, $_POST['password']);

$query = "SELECT * FROM users WHERE username = '$username' AND password = '$password'";
$result = mysqli_query($mysqli, $query);

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