Unique key constraint in Non-clustered index

Question

0.00/5 (No votes)

See more:

Hi All,

Is it mandatory to have unique values in column to create non clustered index with the column in the table?
The column over which the non clustered index is to be created is not the primary key of the table.

Please provide some examples or links that may help a lot.

Thanks

Posted 12-Dec-12 4:17am

sisir patro

Add a Solution

Comments

Herman<T>.Instance 12-Dec-12 10:57am

why? what is your problem?

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

snorkie · Accepted Answer · 2012-12-12T06:57:00

Master Black

No, its not required to have a unique constraint on a non-clustered index. If you were an automotive company, you might have a simple summary table with all of the cars you ever made.

Car_History
VIN Number
Color
Model
Date Produced
Date Sold

The Car_History table would likely have a primary key/index on VIN Number. That would be a unique constraint. But they would probably also have an index on the two date columns for when cars were made/sold. Those columns would have duplicate entries as its easy to produce and sell more than one car each day. In this instance, it would make sense to index these columns. Then summary reports could be run on different time periods to help understand the sales cycle of products.

In this instance, it would be impossible to have unique values in the index as the dates would surly be duplicated!

I hope this helps!

Hogan