Show the difference bw 3-levels of data abstraction in DBMS?

Answer 1

how program independent is differ from program operation independent

Answer 2

the characteristics that allows program-data independence and program-operation independence is called data abstraction.

Answer 3

the  main objectives of DBMS are to store and retrieve information efficiently. all the users should be able to access same data. the designer use complex data structure to represent the data so that the data can be efficiently stored and retrieved. the developers hide the complexity from users through several levels of abstractions.

Data Independence
Data independence means the internal structure of the database should be unaffected by changes to physical aspects of storage because of data independence, the database administrator can change the database storage structure without affecting the users view.
the different levels of data abstraction are:

physical level

it is concerned with the physical storage of information. it provides the internal view of the actual physical storage of data.

logical Level

the logical level describes what data are stored in the database and what relationships exits among those data. logical level describes the entire database in terms of small number of simple structures. the implementation of simple structure of the  logical level may involve complex physical level structures.

View level

view level is the highest level of abstraction. it is the view that the individual user of the database has. there can be many view level abstractions of the same data. the different levels of data abstractions are:-

Database Instances

database change over time as information in inserted & deleted. the collection of information stored in the  database at a particular moment  is called an instance of database.

Database Schema

the overall designs of database is called database schema. a schema is a collection of named objects. schema provides a logical classification of objects in the database.

Answer 4

what is data abstraction in dbms?