Technical Interview Questions and Answers :: DBMS

    1 / 134

    What is database?
    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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    2 / 134

    What is DBMS?
    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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    3 / 134

    What is a Database system?
    Answer:

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

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    4 / 134

    Advantages of DBMS?
    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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    5 / 134

    Disadvantage in File Processing System?
    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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    6 / 134

    Describe the three levels of data abstraction?
    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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    7 / 134

    Define the "integrity rules"
    Answer:

    There are two Integrity rules.
    > Entity Integrity: States that “Primary key cannot have NULL value”
    > Referential Integrity: States that “Foreign Key can be either a NULL value or should be Primary Key value of other relation.

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    8 / 134

    What is extension and intension?
    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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    Tags:Accenture

    9 / 134

    What is System R? What are its two major subsystems?
    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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    10 / 134

    How is the data structure of System R different from the relational structure?
    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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    Tags:Accenture