1. What is an Entity Relationship Diagram? An entity relationship diagram is a graphical representation of an organisation’s data storage requirements. Entity relationship diagrams are abstractions of the real world which simplify the problem to be solved while retaining its essential features. Entity relationship diagrams are used to: identify the data that must be captured‚ stored and retrieved in order to support the business activities performed by an organisation; and identify the data required
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The Entity Relationship Diagram (ERD) depicts a conceptual data model that incorporates some of the important scientific information about the real world. It adopts a natural view that the real world consists of entities and relations (Chen‚ 1976). One objective of the ERD is to create a simple‚ easy to understand and conveniently presented data model consisting of entities‚ attributes‚ relationships and cardinalities. The model serves as tool for database design‚ where the model can facilitate communication
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Entity Relationship Diagram The bellow diagram is what is refered to as an "Entity Relationship Diagram". Its purpose is to show the relationship between different data in the hotel management program ‚ and the actions that are performed on it. And how data from different objects relate to each other. Legend The Data Entities represent data that will need to be stored on the system‚ in general terms. The Relationships represent actions that will occur to the Data Entities‚ or Weak Entities.
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Entity-Relationship Diagrams (ERD) Data models are tools used in analysis to describe the data requirements and assumptions in the system from a top-down perspective. They also set the stage for the design of databases later on in the SDLC. There are three basic elements in ER models: Entities are the "things" about which we seek information. Attributes are the data we collect about the entities. Relationships provide the structure needed to draw information from multiple entities. Generally
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6 Pg 305 2. What is a data flow diagram? Why do systems analysts use data flow diagrams? Answers: A picture of the movement of data between external entities and the processes and data stores within a system. Systems analysts use DFDs to help in the analysis phase by accomplishing the following three things: 1. Requirements Determination 2. Requirements Structuring 3. Alternative Generation and Selection 3. Explain the rules for drawing good data flow diagrams. Answers: Process: A. No process
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Component Diagram Notations The component diagram’s main purpose is to show the structural relationships between the components of a system. In addition‚ component diagrams are useful communication tools for various groups. In creating a component diagram‚ there are different notations that can be used to show the different relationship of each component within the system. The component diagram notation set now makes it one of the easiest UML diagrams to draw: * COMPONENT A component can
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USE-CASE DIAGRAM EXERCISE 1. Draw a use case diagram for an ATM machine with the following functionality. A customer’s interaction with the system involves logging in‚ making withdrawal requests‚ deposit requests‚ and balance inquiry requests. If the customer logs in‚ there is a possibility (although rare) that the system will confiscate the card (for example‚ if the login is incorrect or if the bank determines that the customer’s balance is significantly under zero). Card confiscation involves
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Free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation. A free-body diagram is a special example of the vector diagrams that were discussed in an earlier unit. These diagrams will be used throughout our study of physics. The size of the arrow in a free-body diagram reflects the magnitude of the force. The direction of the arrow shows the direction that the force is acting. Each force arrow in the diagram is labeled
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Food Web Diagram Snake (D) Hawk (D) Coyote (D) Insects (C) Scorpion (C) Lizard (C) Quail (C) Mouse (C) Cactus (P) Grass (P) When you are explaining an ecosystem you have producers‚ consumers‚ and decomposers. Producers are the plants and the tress in the ecosystem that provide the energy to the ecosystem. As for the desert the producers are cactus and grass. The consumers of the ecosystem are in three different kinds‚ they are herbivores‚ carnivores‚ and omnivores. Herbivores are the consumers
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Functional Decomposition Diagram An analyst first must understand an organization’s business functions before he or she can begin developing information systems. The functional decomposition diagram (FDD) is a business planning tool that depicts the hierarchy of business functions‚ processes‚ and subprocesses within an organization that are later described in detail using process models (chapter 6). The exercise of breaking down‚ or decomposing‚ the business functions into processes makes complex
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