This week, we learned that there are four levels of abstraction of a data model. They...

This week, we learned that there are four levels of abstraction of a data model. They are contextual, conceptual, logical, and physical. Briefly explain each level with a focus on the differences between them. When working on the final project for this course, many students go directly to the physical model. What would you say to these students? Why would you say so?

Expert Solution

1. Contextual abstraction: is a high level of abstraction. It is very portable and modular in nature and have been extensively validated

2. Logical Level: is also known as conceptual level. This level also tells us about the relations between the different fields and database tables. This relationship can be many-to-many, one-to-many, many-to-one, the various joins, etc.

3. Physical Level:

The physical level is at the bottom of all the abstraction levels. It describes how data is stored in the database.

Implementation details such as indexing methods like B+ trees or hashing and access methods such as sequential or random access used are described in this level.

Basically, what we do is map the conceptual level to the selected models’ characteristics and constraints.

This makes the DBMS independent of the internal model. Let’s assume that we decide to use relational database management systems; then our conceptual models would be mapped to the internal level.

Yes, it has been observed that many students while doing their projects, directly jump towards physical model (last level of abstraction). To them I would like to say that it's better to follow the top down approach (i.e. from contextual to physical level). Most of them prioritize more to the database management and forgets about the testing and interface part (or sometimes compromises on that part). This approach will let the students to run again and again their objects in order to confirm the implementation.

Let me know if you have any doubts or if you need anything to change. 

If you are satisfied with the solution, please leave a +ve feedback : ) Let me know for any help with any other questions.

Thank You!
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venereology answered 10 months ago

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