Difference between Primary Key and Unique Key

So many people asked me this question; In many interviews also I faced this question.Let’s we have a look into this.

  • Primary Key and Unique key (both) uniquely identifies a row.
  • Unique Key Allows 1 null column, where are Primary key will not allow null values.
  • As per the DBA’s Point of view,  Primary key creates a clustered index,where unique key creates non-clustered index.

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