This PPT is to know different Types of Keys in DBMS.

1. Types of Keys in
Database Management System
Dr. Kamal Gulati

2. Why we have Keys in DB?
• A Key is an attribute or a set of attributes in a
relation that identifies a tuple (record) in a
relation.
• The keys are defined in a table to access or
sequence the stored data quickly and
smoothly.
• They are also used to create relationship
between different tables.
Dr. Kamal Gulati

3. Types of Keys in Database
• 1. Primary Key
• 2. Candidate Key
• 3. Alternate Key
• 4. Super Key
• 5. Composite Key
• 6. Foreign Key
• 7. Unique Key
Dr. Kamal Gulati

4. Primary Key
Employee
EmployeeID
EmployeeName
SSN
DeptID
DOB
• Which is Unique & Can’t be have
NULL Value
• Is the column you choose to
maintain uniqueness in a table at
row level.
• Here in Employee table we can
choose either EmployeeID or SSN
column for a PK.
• EmployeeID is preferable choice
because SSN is a secure (PII) value.
Dr. Kamal Gulati

5. Primary Key
• It is a candidate key that is chosen by the
database designer to identify entities with in
an entity set.
• Primary key is the minimal super keys. In the
ER diagram primary key is represented by
underlining the primary key attribute.
• Ideally a primary key is composed of only a
single attribute.
• But it is possible to have a primary key
composed of more than one attribute.
Dr. Kamal Gulati

6. To define a field as primary key,
following conditions had to be met :
• 1. No two rows can have the same primary key
value.
• 2. Every row must have a primary key value.
• 3. The primary key field cannot be null.
• 4. Value in a primary key column can never be
modified or updated, if any foreign key refers
to that primary key.
Dr. Kamal Gulati

7. Candidate Key
Employee
EmployeeID
EmployeeName
SSN
DeptID
DOB
• Are individual columns in a table
that qualifies for uniqueness of
each row/tuple.
• Here in Employee table
EmployeeID & SSN are eligible
for a Primary Key and thus are
Candidate keys.
• Candidate Keys are super keys
for which no proper subset is a
super key. In other words
candidate keys are minimal
super keys.
Dr. Kamal Gulati

8. Alternate Key
Employee
EmployeeID
EmployeeName
SSN
DeptID
DOB
• Candidate column other the
Primary column, like
if EmployeeID is set for a PK
then SSN would be the Alternate
key.
Dr. Kamal Gulati

9. Super Key
Employee
EmployeeID
EmployeeName
SSN
DeptID
DOB
• If you add any other Column /
Attribute to a Primary Key then it
become a Super Key,
like EmployeeID +
EmployeeName is a Super Key.
• Super key stands for superset of
a key.
• A Super Key is a set of one or
more attributes that are taken
collectively and can identify all
other attributes uniquely.
Dr. Kamal Gulati

10. Composite Key
Employee
EmployeeID
EmployeeName
SSN
DeptID
DOB
• If a table do have a single column
that qualifies for a Candidate key,
then you have to select 2 or more
columns to make a row unique.
• Like if there is no EmployeeID or
SSN columns, then you can
make EmployeeName +
DateOfBirth (DOB) as Composite
Primary Key. But still there can be
a narrow chance of duplicate rows.
Dr. Kamal Gulati

11. Foreign KeyEmployee
EmployeeID
EmployeeName
SSN
DeptID
DOB
Department
DeptID
DeptName
• Here in above tables DeptID of Department
table is Primary Key where as DeptID of
Employee is an Foreign key.
• It means it has referred to another table. This
concept is also know as Referential Integrity.
Dr. Kamal Gulati

12. Unique Key
• Unique key is same as
primary with the difference
being the existence of null.
• Unique key field allows one
value as NULL value.
Employee
EmployeeID
EmployeeName
SSN
EmailID
DOB
Dr. Kamal Gulati

13. Practical Example
• Table R1. Let A,B,C,D,E are the attributes
of this relation.
• A→BCDE (This means the attribute 'A'
uniquely determines the other attributes
B,C,D,E.)
BC→ADE (This means the attributes 'BC'
jointly determines all the other attributes
A,D,E in the relation.)
• Find the following:
– Primary Key
– Candidate Key
– Super Key
– Composite Key
Table – R1
A
B
C
D
E
Dr. Kamal Gulati

14. Answers:
•Primary Key: A
•Candidate Key: A & BC
•Super Key: A, BC, AE, AD & ABC
•Composite Key: BC
Dr. Kamal Gulati

15. (Hope you are able to
understand Different Types of
Keys in Database)
For More Questions /
Queries Feel Free to
Contact me.
Dr. Kamal Gulati

16. Dr. Kamal Gulati
Associate Professor |
University Quality Support Head
Mentoring Programme Coordinator &
Exam Superintendent |
[Ph. D., M.Sc. (Computer Science), M.C.A., M.B.A]
Professional Certifications:
• Certified Microsoft Innovative Educator
• Data Science 101 Certification from Big Data University
• R Language 101 Certification from Big Data University
• SQL Certification from SOLOLEARN.com
• Certified IBM Big Data 101 from Big Data University
• R Program & Python Certified from DataCamp
• Wiley Certified Big Data Analyst [WCBDA]
• Certification on DBMS from IIT Mumbai
• Certified Cisco Certified Network Associate [CCNA]
• Certified Microsoft Certified Professional [MCP]
• Certified Brainbench in (MS Access, MS Project, MySQL 5.7 Administration, Computer
Fundamentals, Advanced Ms. Excel & Windows OS)
• Real-time Advertising Fundamentals Certified from RTA Academy

17. • Worked as Visiting Professor with Stratford University, USA for six months from Jan’2016 to
June’2016.
• Also worked at Bahrain University in Kingdom of Bahrain Sr. I.T. Faculty (Computer Science
Department) for Period of 2 Years.
• Have rich experience in the field of teaching and research in Computer Science and Information
Technology for almost 15+ years in Academia.
• Having experience of working with both private and public institutions and universities as the
lecturer and self-instruction material writer for Information Technology courses.
• Had number of research papers published in national and international journals and conference
proceedings in IEEE and Scopus Index.
• Also chaired various National and International Conferences of repute and associated with
various International Journals as Editorial Board Member for International and National,
Academic Adviser and Research Paper Reviewer.
• My current area of interest: Big Data Analytics, R Software, Internet & Web Technology, IT Project
Management, Decision Support System, Business Analytics, Management Information System,
Database Management System, Data Networking, R Software and Advanced Excel with Visual
Basic Macros.
• Country Visited: USA, Canada, UAE, Bahrain, Oman (Mostly for Teaching and Research Purpose)
Profile of Dr. Kamal Gulati

18. Profile Contd….
• Technical Program Committee for International Conference on Data, Engineering and Applications 2017
(IDEA-2k17) which would be on October 28-29, 2017 at Bhopal. http://www.ideaconference.in
• Advisory Board Committee Member for International Conference on Energy, Communication, Data
Analytics and Soft Computing (ICECDS) which would be on 1-2 August 2017 at SKR Engineering College,
Poonamallee, Tamil Nadu, India. http://ecds.org.in
• Advisory Committee Member for International Conference on Innovative Research in Engineering and
Science which would be on 16-17 June 2017 at Asian Institute of Technology Conference Center
Thailand. http://www.iresconf.org
• Advisory Committee Member for International Conference on Cloud Computing and Internet of
everything which held on 10-11 Feb’2016 at Delhi-NCR. http://www.ccioet.org
• Technical Committee member for InCITe-2016 (International Conference on Information Technology)
Theme - Internet of Things: Connect Your Worlds, IT Summit, Amity University 2016 which held on 06-07
Oct, 2016. http://www.amity.edu/incite2016
• Technical Speaker for Global perspective on IT business “The Changing Scenario” – Big Data on
International Students Conference New Delhi (ISCND) which held on 14-15 Oct, 2016 http://iscnd.com
• Advisory Committee Member for International Conference on Sustainable Computing Techniques in
Engineering, Science and Management which has held on 09-10 Sep’2016 at Delhi-NCR.
http://www.scesm.org
• Technical Program Committee Member for Program Committee Member for International Conference on
Recent Trends IN ICT, Jaipur, India, Aug 18-19, 2017 http://rtict.org
• Program Committee Member for International Conference on Recent Advancement in Computer and
Communication Bhopal, India, (IC-RAC-2017) May 26-27, 2017 http://www.icrac.co.in

19. Profile Contd….
• Editorial Board member for the following International Journals:
– International Journal of Computer Science and Innovation
http://www.infinitysciences.org
– International Journal of Latest Research in Engineering and Technology
http://www.ijlret.com
– International Journal of Latest Trends in Engineering and Technology
http://www.ijltet.org
– International Journal of Application or
Innovation in Engineering & Management
http://www.ijaiem.org
– International Journal for Management http://www.ijm-apm.com
– The International Journal of Emerging Engineering and Embedded Systems
http://www.ijeees.org
– Conference Info http://conferenceinfo.org/tpc.php
• Expert Speaker for Program “Insurance Beyond Doubt” Presented by Oriental
Insurance Co Ltd.
https://www.youtube.com/watch?v=GrvJkN_Zn3Q

20. BOOK, CHAPTER, and CASE STUDY Published
• Published Book on “A Study of Changing Trends in E-CRM of Indian
Insurance Industry” Published by LAP Lambert Academic Publishing, one
of the top researchers and renowned scientists of Germany with ISBN:
3330009543, 9783330009547. The Book available at Amazon.com.
• Published Real Case Study on “IoT Security Considerations for Higher
Education” published on Business Cases - RENVOI 2017 BOOK (The Case
Centre, UK) with ISBN: 978-1-4828-8840-9, Page 63-70. The Book available
at the various online website: Amazon, AbeBooks, Chegg, Barnes & Noble.
• Published Chapter on "Role of eWorld in Insurance Innovation" Published
by Insurance Institute of India (III), 60 Years Diamond Jubilee,
Compendium, Nov 2016 – (Magazine) – One of the premium Insurance
Institute of India.

21. Contact Details
• Email : drkamalgulati@gmail.com
• Website : http://mybigdataanalytics.com
• LinkedIn : https://in.linkedin.com/in/drkamalgulati
• Twitter : @DrKamalGulati
• Skype : kamalgulati7
• Phone: +91-9718361928