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Difference between Unique key and Primary Key

Posted By:Athira Sreejith       Posted Date: December 31, 2008    Points: 15    Category: DataBase    URL: http://www.dotnetspark.com  
 

Difference between Unique key and Primary Key..

1. By default primary key will generate clustered index
where as unique key will generate Non-clustered index.

2. Primary key is a combination of unique and NOT NULLConstraint.
So it can't have duplicate value/any NULLs .
Where as unique Key can have any number of Nulls.


3. A table can have only one Primary key.
But it can have number of unique key.

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Author: PankajGupta         Company URL: http://www.dotnetspark.com
Posted Date: July 14, 2009

Can you please give me some examples where we can use primary key and where we can use unique keys.

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