Types of keys in database management system by Dr. Kamal Gulati
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The document discusses different types of keys used in database management systems. It defines keys as attributes that uniquely identify records in a database table. The main types of keys discussed are primary keys, candidate keys, alternate keys, composite keys, and foreign keys. Primary keys must be unique and cannot contain null values. Candidate keys are attributes that could serve as primary keys. Foreign keys link records between tables.
![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](https://image.slidesharecdn.com/typesofkeysindatabasemanagementsystembydr-170924143107/85/Types-of-keys-in-database-management-system-by-Dr-Kamal-Gulati-16-320.jpg)
Types of keys in database management system by Dr. Kamal Gulati
- 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 : [email protected] • Website : http://mybigdataanalytics.com • LinkedIn : https://in.linkedin.com/in/drkamalgulati • Twitter : @DrKamalGulati • Skype : kamalgulati7 • Phone: +91-9718361928