The REA diagram in Figure 10-11 describes the data model for Apex Supply’s payroll procedures. Themodel consists of only two economic events: Get Time and Disburse Cash. The Get Time event is thereceive half of the economic exchange. This involves a worker (internal agent) giving up his or her time,which is represented by the Employee Services resource. The supervisor (external agent) assumes control ofthe resource. Unlike the tangible economic resources of cash and inventory, time does not have a stock flowelement and cannot be stored. The Get Time event increases time, and various task performance eventssimultaneously decrease time. Earlier in the chapter, the Employee Services resource was discussed as apossible resource to be modeled in the Apex Supply database. In situations in which employee services aredirectly tracked to products produced or services rendered to clients (that is, consulting, legal services, orpublic accounting), it makes sense to model this resource. Because Apex does not track employee time tosuch activities as individual customers served or orders taken, transforming this entity into a physical database table serves no purpose. To maintain consistency with the REA modeling convention that each eventmust be linked to a resource, however, Employee Services is included in Figure 10-11 as a shadow resource(dotted lines) only. It will not be not be modeled in the final enterprise-wide REA diagram
đang được dịch, vui lòng đợi..
