DBMS – Data Abstraction

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Topics: Data Abstraction, DBMS, Software

Transcript Summary

Data abstraction and DBMS related topics are discussed. Data abstraction refers to the act of representing essential features without including the background details or explanations. Database Management System (DBMS) is a software designed to store, retrieve, define, and manage data in a database. The presenter discusses three levels of abstraction: the physical level, logical level, and the view level.

The first level is the physical level, which represents the lowest level of abstraction. The physical level describes how the data is stored and low level data structure into further details. The physical level describes how the data is actually stored, complex low level data structure in detail, and the data structure that data will be saved raw into the database. Some methods that are used in the physical level are the indexed sequential access method, hashing extendible hashing, and clustering.

The second level is the logical level. The logical level describes what data is stored in the database, the relationship that exists among them, and deals with the inter relationship between data and what data is going to be stored that will be decided. Users can see the portion of the database which will be required by the respective user and will be allowed to the user to access. In this way we have discussed this topic, data abstraction. Data in this case is described in terms of a small number of relatively simple structures, not like the detailing structure or in the physical level. The third level is the view level. The view means a scope or permission with the help of which the user can see a portion of the database or subset of the database. The view level is the highest level of abstraction that describes only part of an entered database. Many users of the database system do not need all this information. Instead they need to access a part of the DBMS. If a portion of the database is made available, that means the full database will not be available because the full database will not be available to the user. The user also does not require it or due to the safety of the database, all data should not be made available to a single user. This also means the level of data abstraction of that data will be made available to the respective user.

There are different levels of data abstraction that were discussed. The lowest level was the physical level, which deals with how the data will be stored and drawn into the database. The logical level will deal with the inter relationship between data and what data is going to be stored that will be decided and in case of you label it will be divided into levels of abstraction of the users and through these views. Users can see that portion of the database which will be required by the respective user and which will be allowed to the user to access the different data that is made available inside the database.

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DBMS – Database System Applications

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