What is a unique key?

Posted by  Sanat Shukla
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  1. What is a unique key?

    The Unique key constraint uniquely identified each record in the database. This provides uniqueness for the column or set of columns.

    The Primary key constraint has automatic unique constraint defined on it. But not, in the case of Unique Key.

    There can be many unique constraints defined per table, but only one Primary key constraint defined per table.