object DatabaseConnection {
        private val Connection = ...

        private object PasswordDevice {
            def check(pw1: String, pw2: String) = ...
            def encrypt(password: String) = ...
        }

        object LoginDevice {
            private val GetUserStatement = Connection.prepareStatement("SELECT Name, Password, Rights FROM Users WHERE UPPER(Name) = UPPER(?)")

            def login(username: String, password: String) = {
                GetUserStatement.setString(1, username)
                val userResult = GetUserStatement.executeQuery
                if ( !userResult.next )
                    throw User.NotFoundException
                if ( !PasswordDevice.check(password, userResult.getString("Password")) )
                    throw User.WrongPasswordException
                new User(userResult.getString("Name"), ...)
            }
        }


        object RegisterDevice {
            private val RegisterStatement = Connection.prepareStatement("SELECT Name, Password, Rights FROM Users WHERE UPPER(Name) = UPPER(?)")
            private val GetKeyStatement = Connection.prepareStatement("SELECT Key FROM Keys WHERE UPPER(Key) = UPPER(?)")
            private val InsertStatement = Connection.prepareStatement(s"INSERT INTO Users VALUES(?, ?, ...)")
            private val DeleteKeyStatement = Connection.prepareStatement("DELETE FROM Keys WHERE Key = ?")

            def register(name: String, password: String, key: String) = {
                RegisterStatement.setString(1, name)
                GetKeyStatement.setString(1, key)
                val userExistsResult = RegisterStatement.executeQuery
                val keyValidResult = GetKeyStatement.executeQuery
                if ( userExistsResult.next ) throw User.AlreadyExistsException
                if ( !keyValidResult.next ) throw User.InvalidKeyException
                InsertStatement.setString(1, name)
                InsertStatement.setString(2, PasswordDevice.encrypt(password))
                InsertStatement.executeUpdate()
                DeleteKeyStatement.setString(1, key)
                DeleteKeyStatement.executeUpdate()
                new User(name, ...)
            }
        }


        object RequestDevice {
            private val RequestStatement = Connection.prepareStatement("SELECT Request.* FROM Request WHERE ID = ?")

            def request(id: String) = {
                RequestStatement.setString(1, id)
                val result = RequestStatement.executeQuery
                if(!result.next)
                    throw Request.InvalidIDException
                new DataElement(result.getString("id"), ...)
            }
        }

        ...
    }