Explain why the external entities on the context-level diagram are not found on the entity-relationship diagram.
Introduction
An external entity represents a business, a person or a department, which can be used to send and receive data from a system (Kendall and Kendall, 2008). The context-level diagram is used to depict the computer system and its relation to the external environment. The entity relationship diagram indicates the relationship that exists or connects different data entities. One entity may be used to connect a single or multiple entities.
Thus, a context level diagram shows the linkage between the external entities and the computer system. According to Kendall and Kendall (2008), the context level diagrams will indicate the data flow from the external entities to the system by using data flows. The external entities provide data but are not part of the system. Additionally, as the context level diagram only shows the linkage between the external entities and the system, it does not show a higher level of what exactly happens in the system. The context level diagram provides an overview or scope of the system from a general perspective. Consequently, the entity relationship diagram shows what actually happens in the system. The entity relationship diagram shows how data entities relate to each other. These data entities are obtained from the external entities found in the context level diagram (Kendall and Kendall, 2008). Therefore, the entity relationship diagram keeps track of the data entities acquired from the external entities and the context diagram shows the external entities, which supply or receive data from the system
Conclusion
The entity relationship diagram helps one to understand the organization system and how data is stored in the organization. It shows how a system functions. The context level diagram does not indicate how a system functions and just provides a general overview. The entity relationship diagram will indicate the data stores that were supplied from the external entities.
Explain why the entities management and faculty are found on both sides of the process on the context-level diagram
Introduction
The context level diagram shows the scope of the system and its association with its environment (external entities). According to Dennis, Wixom and Roth (2008), the context diagram will indicate the overall business process. This implies that data flows to and from the system are indicated.
The entity's management and faculty represent the sources of the data and the response from where the data will be obtained. This means that they receive and send information. Thus, the management and faculty entities make inquiries to the computer inventory system. This indicates that they send information. To receive the data, the computer system has to send data back to the two entities. This means that to clear show how the data flows the management and faculty entities have to be placed on both sides of the context diagram. Further, including them on both sides of the context diagram prevents disorder, which would be the case if they have been placed on one side and arrows used to show the data flow.
Conclusion
Inclusion of entities on both sides of the context diagram helps to avoid cluttering of the context diagram, which may help in reducing any form of confusing to an analyst. This situation is applied in systems where the entities supply and receive the information sent to the same system.
References
Dennis, A., Wixom, B. H., & Roth, R. M. (2008). Systems Analysis Design (4th Ed.). Chichester:
John Wiley.
Kendall, K. E., & Kendall, J. E. (2008).Systems Analysis and Design (7th Ed.). Upper Saddle
River, N.J.: Pearson/Prentice Hall.
