Answer: A database is a logically coherent collection of data with some inherent meaning, representing some aspect of real world and which is designed, built and populated with data for a specific purpose.

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Answer: It is a collection of programs that enables the user to create and maintain a database. In other words, it is general-purpose software that provides the users with the processes of defining, constructing and manipulating the database for various applications.

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Answer: The database and DBMS software together are called as Database system.

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Answer: 1. Reduces Data Redundancy 2. Maintains Data Consistent 3.Query to access data 4. Security 5. Easier access by tables

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Answer: 1. Redundant Data 2. Inconsistency 3. Not easy to access data. 4. No security 5. Concurrent access is not allowed.

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Answer: Physical Level - This is the lowest level of data abstraction which describes which describes how the data is to be stored in the database. Logical level - The level describes the data in the database as well as relations between these database. View Level- This is the highest level of data abstraction , only some part of actual database is viewed to the user.

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Answer: There are two Integrity rules.

> Entity Integrity: States that â€œPrimary key cannot have NULL valueâ€

> Referential Integrity: States that â€œForeign Key can be either a NULL value or should be Primary Key value of other relation.

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Answer: The description of data base is called in tension or database schema,which is specified during database design and is not expected to change frequently.



The actual data in a database may change quite frequently.The data in a database at a particular moment in time is called a extension or database state or snapshot.



Source:- Extension and intension

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Answer: System R was designed and developed over a period of 1974-79 at IBM San Jose Research Center. It is a prototype and its purpose was to demonstrate that it is possible to build a Relational System that can be used in a real life environment to solve real life problems, with the performance at least comparable to that of the existing system.

Its two subsystems are

> Research Storage

> System Relational Data System.

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Answer: Unlike Relational systems in System R

> Domains are not supported

> Enforcement of candidate key uniqueness is optional

> Enforcement of entity integrity is optional

> Referential integrity is not enforced

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