Term
Discuss the importance of
data modeling |
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Definition
| Data models are a great communication tool because they faciliate interaction and communication between the designers, programmers and end users. In essence it does not allow one party's bias towards a certain view of a data (what they consider to be most important) to take hold. |
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Q2:
What is a business rule and what is its importance in data modeling? |
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Definition
| A business rule is a brief, precise and unambiguous description of a policy, procedure, or principle within a specific organization. They are important in data modeling because they set the stage for the proper identification of entities, attributes, relationships and constraints. |
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Q3:
How do you translate business rules into data model components? |
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Definition
You translate business rules into data model components by following the basic principles:
a noun in a business rule will translate into an entity in the model.
a verb (active or passive) associating nouns will translate into a relationship among the entities. |
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Term
Q4:
What languages emerged to standardize the basic network data model?
Why was such standardization important to users and designers?
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Definition
| DML and DLL emerged to standardize the basic data model. This standardization was important to both users and designers because it allowed for the conception of the schema and subschema. |
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Term
Q5:
Describe the basic features of the relational data model and discuss their importance to the end user and the designer. |
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Definition
The basic feature of the relational data model include:
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The importance of the relational data model was essentially that its simplicity set the stage for genuine database revolution. |
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Term
Q6:
Explain how the entity relationship (ER) model helped produce a more structured relational database design environment. |
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Definition
| The ER model helped produce a more structured relational database design environment because it allowed designers to visually see entities and their relationships. |
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Term
Q7:
Use the scenario described by "A customer can make many payments, but each payment is made by only one customer" as the basis for an entity relationship diagram (ERD) representation. |
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Definition
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Term
Q8:
Why is an object said to have greater semantic content than an entity? |
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Definition
An object is described by its factual content and also includes information about relationships between the facts within the object as well as information about its relation to other objects. Entities on the other hand, stops at being described by its factual content.
The term semantic indicates meaning, thus an object obviously has more semantic content since it contains more information. |
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Term
Q9:
What is the difference between an object and a class in the object-oriented data model (OODM)? |
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Definition
| In the OODM, an object contains both data and their relationships. Meanwhile, a class is a group of objects that share similar objects with shared structure (attributes) and behavior (methods). |
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Term
Q10:
How would you model question 7 with an OODM?
Use fig. 2.4 as your guide. |
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Definition
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Q11:
What is an ERDM, and what role does it play in the modern (production) database environment?
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Q12:
In the terms of data and structural independence, compare file system data management with the five data models discussed in this chapter.
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Definition
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Term
Q13:
What is a relationship, and what three types of relationship exist?
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Definition
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Q14:
Give an example of each of the three types of relationships.
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Q15:
What is a table, and what role does it play in the relational model?
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Q16:
What is the relational diagram? Give an example.
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Q17:
What is logical independence?
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Q18:
What is physical independence?
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Q19:
What is connectivity?
(Use Crow's Foot ERD to illustrate connectivity) |
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Definition
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