10 Basic Easy DBMS aptitude Questions


1. What is DBMS?


It is a collection of programs that enables user to create & maintain a database.


In other words it is general-purpose software that provides the users with the processes of


defining, constructing & manipulating the database for various applications.


2. What is Database?


A database is a logically coherent collection of data with some inherent meaning,


representing some aspect of real world & which is designed, built & populated with


data for a specific purpose.




3. What is a Database system?


The database & DBMS software together is called as Database system.



4. Advantages of DBMS? Redundancy is controlled. Unauthorised access is restricted. Providing multiple user interfaces. Enforcing integrity constraints. Providing backup & recovery.



5. Disadvantage in File Processing System? Data redundancy & inconsistency. Difficult in accessing data. Data isolation. Data integrity. Concurrent access is not possible. Security Problems.



6. Describe the three levels of data abstraction?


The are three levels of abstraction: Physical level: The lowest level of abstraction describes how data are stored. Logical level: The next higher level of abstraction, describes what data are stored in


database & what relationship among those data. View level: The highest level of abstraction describes only part of entire database.


7. Define the "integrity rules"


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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.



8. What is extension & intension in DBMS?


Extension -


It is the number of tuples present in a table at any instance. This is time


dependent.


Intension -


It is a constant value that gives the name, structure of table & the


constraints laid on it.



9. What is System R? What are its two major subsystems?


System R was designed & developed over a period of 1974-79 at IBM San Jose


Research Center. It is a prototype & 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 performance at least comparable to that of existing system.


Its two subsystems are Research Storage System Relational Data System.



10. How is the data structure of System R different from the relational DBMS structure?


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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