What are the best practices for structuring classes in PHP to handle database queries and encryption algorithms?

When structuring classes in PHP to handle database queries and encryption algorithms, it is recommended to separate concerns by creating separate classes for each functionality. This helps maintain code readability, reusability, and scalability. For database queries, consider using a Data Access Object (DAO) pattern to encapsulate database interactions, while for encryption algorithms, create a separate Encryption class to handle encryption and decryption operations.

// Database class for handling database queries
class Database {
    public function query($sql) {
        // Database query logic here
    }
}

// Encryption class for handling encryption algorithms
class Encryption {
    public function encrypt($data) {
        // Encryption logic here
    }
    
    public function decrypt($data) {
        // Decryption logic here
    }
}