04 data abstraction

Data Abstraction

1. Database systems include complex data structures.
2. developers use abstraction To make the system
   1. make the system efficient in data retrieval
   2. reduce complexity for users by hiding irrelevant details.
3. Keep away the complex data from the user and remove the complications
4. So that the user can comfortably access the data they want
5. The main purpose of data abstraction is to hide irrelevant data and provide an abstract view of the data.
6. With the help of data abstraction, developers hide irrelevant data from the user and provide them the relevant data.
7. By doing this, users can access the data without any trouble, and the system will also work efficiently
8. In DBMS, data abstraction is performed in layers which means there are levels of data abstraction.

Levels of Data Abstractions in DBMS

1. Physical or Internal Level:

1. The physical or internal layer is the lowest level of data abstraction in DBMS
2. It is the layer that defines how data is actually stored in the database.
3. It defines methods to access the data in the database
4. where the data is actually stored, the actual location of the data that is being stored by the user.
5. DBA decide that which data should be kept at which particular disk drive, how the data has to be fragmented, where it has to be stored etc.
6. They decide if the data has to be centralized or distributed.
7. data here is actually stored in the form of files only.
8. The DBA’s role is to manage the data in the database at the physical or internal level.

2. Logical or Conceptual Level:

1. The logical or conceptual level is the intermediate or next level of data abstraction.
2. After taking the raw data from internal level, the structure of data is defined at logical level.
3. It explains,
   1. what data is to be stored in the database
   2. relationship is between them.
4. describes the structure of the entire data in the form of tables
5. The logical level or conceptual level is less complex than the physical level.
6. With the help of the logical level, Data Administrators (DBA) abstract data from raw data present at the physical level.

3. View or External Level:

1. View or External Level is the highest level of data abstraction.
2. There are different views at this level That define the parts of the overall data of the database.
3. This level is for the end-user interaction
4. at this level, end users can access the data based on their queries.
5. He/she does not get the entire database, but depending on the queries made from the front-end the user gets to see the data.
6. It may be a single data from the entire database or a collection of data in tabular format.
7. Multiple views of the same data are available to the user
8. the representation can be a table, a graph, or a pie chart.