DBMS Interview Questions

1) What is DBMS?

DBMS (Data Base Management System) is a technology for managing data of database i.e. Create, Update, Delete, Alter.

2) What is a Database System?

It is defined as collection of database and DBMS software that works in synchronized order.

3) Enlist the advantages of DBMS.

  • Data Independence: It provides an abstract view of the data for insulating application code.
  • Data Integrity
  • Data Security
  • Data Backup and Recovery

4) Enlist the Component of DBMS.

  • Users
  • Database Application
  • DBMS
  • Database

5) Give the type of database architecture

  • Centralized
  • De-centralized
  • Hierarchal

6) What are the layers in database architecture?

DBMS architecture can be single tier or multi-tier but most widely used is 3-tier its layer as follows:

  • Presentation Layer
  • Application Layer
  • Database Layer

7) How many types of database languages?

  • DDL (Data Definition Language): CREATE, ALTER, DROP
  • DML (Data Manipulation Language): SELECT, UPDATE, INSERT
  • DCL (Data Control Language): GRANT & REVOKE.
  • TCL (Transaction Control Language): COMMIT, ROLLBACK.

8) Define Database Schema.

Database Schema is a logical blue print of the database and database instance. Some terms associated with it is:

  • Relation
  • Attribute
  • Domain
  • Tuple

9) Give the types of schema in DBMS

  • Physical Schema
  • Logical Schema
  • View Schema

10) What is ER-Diagram?

ER-Diagram represents an Entity Relationship Diagram i.e. How data is related and communicated with each other.

11) Give the types of Relationships.

  • One to One
  • One to Many
  • Many to One
  • Many to Many

12) List the drawbacks of File Processing System.

FPS (File Processing System) has many drawbacks due to which DBMS come in action. Here are some drawbacks i.e. these are not present:

  • Consistency
  • Data Integrity
  • Data Security
  • Data Accessing
  • Data Redundancy
  • Data Isolation

13) Define Normalization in DBMS?

Normalization is a process to analyze the relation schema according to their resp0ective functional dependencies. Basically, it is used to minimize redundancy.

14) Define De-normalization in DBMS?

It allows increased performance of database which is achieved by adding redundant data and eliminating complex data.

15) What is Functional Dependency?

It is the starting point of normalization. It exists only if the relation between the two attributes allows to uniquely determining the corresponding attribute value.

16) Enlist the Database Normalization rule.

  • 1NF (First Normal Form): Each and every column is Unique.
  • 2NF (Second Normal Form): It should already be 1NF and all attributes within the entity should depend upon unique ID of entity.
  • 3NF (Third Normal Form): In this no column entry should be dependent on any other entry level values and should be 2NF.
  • BCNF (Boyce Codd Normal Form): All tables should have only one primary key and it should be 3NF.

17) What is weak entity set?

Weak Entity set is said to those set which doesn’t have sufficient attribute to form a primary key.

18) Give the Integrity Rules in DBMS.

There exist some rules

  1. Entity Integrity
  2. Referential Integrity
  3. Domain Integrity
  4. User-Defined Integrity

19) Describe Extension and Intention.

Extension: It is described as the number of tuples present in a table at any instance also, it is time dependent.

Intension: It provides a constant value that enlist the name, structure of table and the constraints laid on it.

20) Enlist the type of Manager in Program Module.

  • Storage Manager
  • Buffer Manager
  • Transaction Manager
  • File Manager
  • Authorization/Integrity Manager

21) What is Join?

Join is used to combine data from two or more tables, based on a common fields between them.

22) Enlist the type of Join?

  • Inner Join: It provides the result on intersection between the two tables.
  • Left Join: It provides the result on intersection as well as left table for which the join condition is met.
  • Right Join: It provides the result on intersection as well as right table for which the join condition is met.
  • Full Join: It provides the result on selection of all record from both table.

23) What is Identity?

Identity is a column that automatically generates numeric values. In this column we can set the start value and can increment it.

24) What is Trigger?

A Trigger is a code that associated with insert, update or delete operations. The code is executed automatically whenever the associated query is executed on a table.

25) What is stored procedure?

A stored procedure is like a function that contains a set of operations compiled together. It contains a set of operations that are commonly used in an application to do some common database tasks.

26) What is DML compiler?

A DML (Data Manipulation Language) compiler is used to translate DML statements into query language. Translated language is in low level instruction.

27) What is RDBMS?

Relational Data Base Management Systems (RDBMS) are database management systems that maintain data records and indices in tables.

28) List some of the properties of a relation?

Relations have a unique name and no multivalued attributes exist. Each row is unique and each attribute within a relation has a unique name.

29) What is a Catalog?

Catalog is a table which contains the information such as structure of each file, the type and storage format of each data item.The information stored in the catalog is called Metadata.

30) Enlist four applications of triggers?

  • Providing default values
  • Enforcing data constraints
  • Updating views
  • Enforcing referential integrity

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