Chapter 4, Problem 1RQ

What is the difference between a PRIMARY KEY constraint and a UNIQUE constraint?

Explanation of Solution

  Difference between PRIMARY KEY and UNIQUE constraint

  

PRIMARY KEY	UNIQUE
There will be only one primary key per table.	But in the case of unique constraint, there will be more than one unique constraint.
Primary key constraints are not nullable.	Unique key constraints are nullable.
When a primary key is defined, then a clustered index is automatically created.	When a unique key is defined, then a non-clustered index is generated.