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

Assignments, i have assignments I don''t have time to finish because of wo...

i have assignments I don''t have time to finish because of work and other assignments, can you help with this? All are from the book Darabase design, application development and a

Data warehouse, 1) Define a job scheduling strategy that will meet business...

1) Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pict

Explain the b+ tree, Explain the B + tree? B + tree is a type of tre...

Explain the B + tree? B + tree is a type of tree which denotes sorted data in a way that permits for efficient insertion, retrieval and removal of records, each of which is

ER-diagram, The State of NewYork certifies firefighters throughout state an...

The State of NewYork certifies firefighters throughout state and keep track all of them, as well as of the state’s fire departments. Each fire department has unique department numb

Function module, When a function module is activated syntax checking is per...

When a function module is activated syntax checking is performed automatically. YEs, a function module is activated syntax checking.

Define signal, Define Signal. It allows methods to respond to events tr...

Define Signal. It allows methods to respond to events triggered by themselves or by other processes. Each signal corresponds to an exacting event. A signal is represented in Sy

Entity identifier key attributes, An entity type usually has an attribute w...

An entity type usually has an attribute whose values are distinct for every individual entity in the collection. Such an attribute is known as a key attribute and its values can be

Method of analyzing association traversal, Analyzing Association Traversal ...

Analyzing Association Traversal Till now, we have supposed that associations are bi-directional. But in the case of traversal, it is in only one direction in any application,

Normalization, Normalize the given relation to 3NF, justifying each step

Normalize the given relation to 3NF, justifying each step

Windows 8 Administrative Tools, Which two tools are used to administer user...

Which two tools are used to administer users for Active Directory?

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