What is the difference between primary key and a unique key, Database Management System

Assignment Help:

What's the difference between a primary key and a unique key?

Both primary key and unique key enforces uniqueness of the column on which they are explained. But by default primary key creates a clustered index on the column, where are unique makes a no clustered index by default. Another main difference is that, primary key doesn't permit NULLs, but unique key permits one NULL only.

 


Related Discussions:- What is the difference between primary key and a unique key

Development of large scale distributed real systems, Question: (a) What...

Question: (a) What are the challenges in the development of Large Scale Distributed Real Systems? (b) What is backward engineering and forward engineering in a design packa

What is a records management consultation, What is a records management con...

What is a records management consultation? Our organization is an authority for disseminating your specific requirements and giving you with a solution to effectively manage yo

What is database files , The database files accept the actual data and ...

The database files accept the actual data and are typically the biggest in size. Depending on their shape, the tables for all the user operation can go in one database file-but

Scope of traffic data management, A TDMS project plan is not a typical Info...

A TDMS project plan is not a typical Information Technology project plan; therefore, a traffic data project has several unique characteristics: Traffic data management system

Consider relational schema and construct algebra query, Consider the follow...

Consider the following relational schema: PERSON (SS#, NAME, ADDRESS) CAR (REGISTRATION_NUMBER, YEAR, MODEL) ACCIDENT (DATE, DRIVER, CAR_REG_NO) OWNS (SS#, LICENSE) Constru

Modelling and normalisation, Task Part A. Create an ERD from a business pro...

Task Part A. Create an ERD from a business problem. (50 marks) Read the following problem and complete the tasks listed below. THE ABS Blood Bank Australian Blood Services (ABS) i

What are composite objects, What are composite objects? Objects that ha...

What are composite objects? Objects that have other objects are known as complex objects or composite objects.

Explain clustering file organization, Explain Clustering file organization ...

Explain Clustering file organization (i) Determine if a record of file is physically ordered on a nonkey field - that does not comprise a different value for each record - that

Describe file organisation, Describe file organisation? A file is organ...

Describe file organisation? A file is organized logically as a sequence of records. These records are mapped onto disk blocks. A) Fixed-Length Records Type deposit=record

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd