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What Is The Difference Between Primary Key & Unique Index ?

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PRIMARY : a relational database constraint. Primary key consists of one or more COLUMNS that UNIQUELY IDENTIFY a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical OBJECT that stores only unique values. There can be one or more unique indexes on a table.

Primary : a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table.


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