Week 2: Project Entities and Relationships
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As you further consider the information problems and design of the database from your week 1 discussion
Name two-to-five entities (also known as entity classes in your text) that will be part of your database.
Explain why you have chosen these entities.
Using the Chen format as shown and discussed in the Oppel text, draw an entity-relationship (E-R) diagram for two of the entities, name the identifier for the selected entitiies, and attach the drawing to your discussion post. Remember, an entity-relationship requires at least one other entity. Use a software program or Microsoft Word symbols to depict your diagram aspects
Project Entities and Relationships Example
Guidelines
Purpose
Week 2 TD: Project Entities and Relationships
Reflect on your problem and name up to five entities (also known as entity classes in your text) that will be part of your database. Explain why you have chosen these entities. Draw an entity-relationship (E-R) diagram for one of the entities, name the identifier for the selected entity, and attach the drawing to the discussion post. (It is acceptable to draw the E-R diagram by hand or to use software and scan the diagram as a PDF file.)
To continue development of your database project, you will be working with data entities or data classes generated from your problem descriiption and those sample questions from last week. You are not limited to just those questions, though. Thinking in advance of what you will ask the database can ensure that you have the right data names and, ultimately, the data values to supply the answers. In other words, what do you want to be able to extract or retrieve about your problem? You must then reflect on the data that you must input in order to obtain the output that you need.
Do not worry about getting the E-R diagram into a perfect form – the purpose is to learn about E-R diagrams and to determine if your data entities make sense and have clear relationships. In the discussion threads, be sure to ask questions and help each other find the answers.
Tips for Developing Effective E-R Diagrams
1. Name each entity and its attributes
a. Are all of the entities listed?
b. Are there any duplicate entities? If so, remove the duplicates, since each entity should appear only once in each diagram.
2. Describe the relationships between the entities.
a. Does each of these relationships exist, or are they necessary?
b. Have you missed any relationships?
c. Are there any duplicate relationships? If there is redundancy, it must be removed.
3. Color coding can help you to quickly visualize the E-R Diagram. You should use colors to demonstrate
the key portions of the diagram. This is a technique that can be used with a team to show what each person thinks is important. Ask everyone to create their own E-R diagram and color code what they fill is the most important. Comparing E-R Diagrams can be an eye opener. When each person shares their diagram, it can help to get everyone on the same page.
Example E-R Diagram Format
E-R Diagram Enhanced with Color
Can you fill in the other attributes?
What would you enhance with color?
