According to [PoEAA], this definition is "A Transaction Script organizes all this logic primarily as a single procedure, making calls directly to the database or through a thin database wrapper." For example, when I buy a book on a ecommerce shop, the system executes a series of action, including receiving a book id and customer session, getting a book detail and customer detail from the database, and inserting an order into the database. These actions are organized in a transaction script. Usually, a database transaction maps to a transaction script. So it is easily to implement data isolation. 2. Pattern Practice: The Revenue Recognition Problem