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What are the difference and similarities between primary key foreign key and unique key?


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April 02, 2009 5:57AM

primary key: primary creates a clustered index on the

column and it doesn't allow null values.

unique key: unique key creates non clustered index by allows "one null value".

foreign key: A foreign key (FK) is a column or combination

of columns used to establish and enforce a link between the

data in two tables.

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