What do you mean by the term Data Abstraction used in DBMS? How is it useful? Why is it used? What are its advantages?
The Term Data Abstraction With Respect To Dbms
Data abstraction basically refers to the process of hiding important data from the prying eyes of other users. Data like password, card number, etc. which cannot be disclosed is kept hidden with the help of the method called as data abstraction. It helps in keeping our personal information and data that is important to us secure. This process occurs on the view level of the DBMS three- tier architecture.
The Term Data Abstraction With Respect To Dbms
Data abstraction is the cutback of a specific body of data to a cut down or basic representation of the whole. Generally, abstraction is the process of removing characteristics from something to be able to decrease it to a set of important characteristics. In database design, data abstraction is normally the initial step.
A complete or whole database is much more complex to be developed by a system without creating first a basic framework. With data abstraction, it is possible for developers to begin from important elements, the data abstractions, and then increasingly add data detail to build the final system. The following are the four levels of data abstraction:
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* External level – this is the highest level of data abstraction. At this level, data appears as rows and columns to users. Users can view full or partial data according to the business requirement.
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* Logical / Conceptual level – this is the next level of data abstraction which describes the actual data stored in the database and appears in the form of tables and connects them using mapping.
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* Internal level – this is one of the intermediary levels which, in most cases, are not mentioned because they usually say that there are only three levels of data abstraction. This level depends on the DBMS software.
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* Physical level – this is the lowest level of data abstraction. It describes how data is literally stored in the physical memory such as hard drives, magnetic tapes, and others. In this level, the file organization methods such as sequential, B+ tree, or hashing comes in.
