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Difference between Primary key and unique key?

Answer Posted / sohini ghosh

In RDBMS, a unique key can uniquely identify each row in a
table, and is closely related to the Super key concept. A
unique key comprises a single column or a set of columns.it
can be null.


A primary key is a special case of unique key. Primary keys
may consist of a single attribute or multiple attributes in
combination.It can't be null..

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