Difference Between Primary Key and Unique Key
Every SQL programmer is supposed to have a better knowledge of Primary and Unique key. As I have visited many places and observed this that it’s the basic question being asked. I have decided to share this for those who are fresh and preparing for some kind of interview.
Primary Key:
1. Primary key does not accept null values.
2. There is only one primary key in a table.
3. Clustered index is created in Primary key.
4. Primary key allows each row in a table to be uniquely identified and ensures that no duplicate rows exist.
Unique Key:
1. Using Unique key, Null values are accepted.
2. More than one unique key can be defined there in a table.
3. Non-Clustered index is created in unique key.
4. Unique key constraint is used to avoid the duplication of key values within the rows of a table.
If you know some more differences, Then comment here or mail me. I will update post.
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