Is there any difference between the primary key and unique key?


Posted On: Feb 22, 2018


There is, of course, a difference between the primary and unique key

Primary key

  • It enforces the uniqueness of column in a table.
  • It does not allow the nulls.
  • It chooses default cluster index

Unique key

  • It allows one null value.
  • It doesn't enforce uniqueness of a column in a table.
  • It chooses a default non clustered index.

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