Translate to Tamil

Earn Money


Best Offers

Amazon Best Offers

Offers

Best Online Offers

Amazon Offers

Earn Money Short URL

Thursday, 6 January 2011

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 defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered index by default. Another major difference is that, primary key doesn't allow NULLs, but unique key allows one NULL only.

 Share This Post


No comments:
Write comments

Contact Form

Name

Email *

Message *

Infolinks

© 2014