Difference between Primary Key and Unique Key

By default, primary key creates clustered index on the column and then enforces the uniqueness of the column whereas the unique key, by default creates a non-clustered index.

Primary Key

  • By default, creates Clustered index
  • Doesn’t allow null
  • Table can have only one Primary Key ( Can include multiple columns together )

Unique Key

  • By default, creates non clustered index
  • Accepts null value
  • Table can have many unique keys
If you enjoyed this post, please consider leaving a comment or subscribing to the RSS feed to have future articles delivered to your feed reader.

Leave a Reply


Interesting BlogPosts to read

Column Alias and Square brackets in SQL Query.
When we want to specify a alias for a column in SQL Query , we tend to use the double quotes or sing...
How to get the MAX row with group by in LINQ query using C# ?
Below is a sample code snippet demonstrating how to retreive the max row with the group by in LINQ Q...
Webinar - The Shortcomings of SQL for SharePoint Sync
Redmond Magazine is hosting a webinar on the topic "The Shortcomings of SQL for SharePoint Sync" on ...