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RELATIONAL DATABASE MANAGEMENT SYSTEM (RDBMS)
RDBMS is a relational DBMS in which tables are linked to each other based on the common field. In addition
to all the advantages of DBMS (as discussed), RDBMS helps in the management of a database in a broader
way. A relational database is defined as a collective set of multiple datasets organised into tables. Most of the
relational databases use Structured Query Language (SQL) as a primary way to interact with the database. SQL
provides a powerful and easy-to-use interface for tasks such as data retrieval, manipulation and management.
In an RDBMS, data is organised into related tables connected by keys, such as primary key, composite key,
etc. These keys ensure data integrity and facilitate efficient querying across multiple tables.
For example, assume that in an organisation, there are three different tables that contain information about
Employee, Salary and Attendance, separately. The first table contains information of each employee, such as
Employee Code, Name, Address, Department, etc. The second table contains salary details of each employee,
such as Employee Code, Basic Salary, PF, HRA, etc. Similarly, the third table contains information about
monthly attendance of each employee including the Employee Code.
To generate an employee’s payslip, the Employee Name and Address can be retrieved from the first table,
Basic Pay and other allowances from the second table, and Monthly Attendance from the third table. This
information is interrelated through the Employee Code. An RDBMS, such as Microsoft Access, Oracle,
LibreOffice Base, or OpenOffice Base can easily manipulate and organise such relational data.
Table: Employee
Columns or Fields or Attributes
Primary EMP_CODE NAME DEPARTMENT ADDRESS
Key
E1 Rahul IT Rama Garden, New Delhi
Rows E2 Kapil Marketing New Friends Colony, New Delhi Cardinality
Records E3 Manoj HR Ram Park, Lucknow (No. of Rows) = 5
or Tuples
E4 Mukesh Finance Sanjay Lane, New Delhi
E5 Rajesh Sales Vikas Puri, New Delhi
Degree (No. of Columns) = 4 Data Value
Basic Terminologies of RDBMS
Some of the important terms of RDBMS are as follows:
Entity: It is a real-world object about which information is to be stored in a database. For example, if we
want to store information about an entity Employee in an Office, then we need to have his EMP_CODE,
NAME, DEPARTMENT, ADDRESS, etc. These details associated with the entity are called attributes. Each
entity is a collection of these attributes associated with it. So, EMP_CODE, NAME, DEPARTMENT, etc., are
attributes associated with the entity employee. These attributes are represented in the form of columns.
Keys: A key is a field or combination of fields that uniquely identify a record(s) from a table. Keys are
essential for maintaining data integrity and establishing relationships between tables in RDBMS.
Data Value: Data value are the raw information, represented in numeric, character or alphanumeric form.
Introduction to Database Management System 211

