What are some best practices for sanitizing and filtering user-generated content in PHP before storing it in a database?

Sanitizing and filtering user-generated content in PHP before storing it in a database is crucial to prevent SQL injection attacks and ensure data integrity. One common approach is to use functions like `mysqli_real_escape_string()` to escape special characters and `htmlspecialchars()` to prevent XSS attacks.

// Sanitize user input before storing in the database
$user_input = $_POST['user_input'];
$clean_input = mysqli_real_escape_string($connection, htmlspecialchars($user_input));

// Store the sanitized input in the database
$sql = "INSERT INTO table_name (column_name) VALUES ('$clean_input')";
mysqli_query($connection, $sql);