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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.



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