What is the difference between unique key and primary key?

Asked By suyashupadhyay 10 points N/A Posted on - 10/27/2011

What is the difference between unique key and primary key?

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Answered By Javaid 0 points N/A #96809

What is the difference between unique key and primary key?

A UNIQUE constraint is similar to PRIMARY key, but you can have more than one UNIQUE constraint per table.

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Answered By John10 0 points N/A #96810

What is the difference between unique key and primary key?

After clearly reading your question the following is the notable difference between the two items.

·         A unique key although similar to a primary key can contain more than one unique constraint in a given table whereas a primary key cannot

·         A unique key accepts null values whereas a primary key does not

·         A unique key is used for the purpose of preventing duplication of key values within a given row of a table as well as allowance of null values whereas the primary key is used to uniquely identify a given row in a table as well as ensuring that no duplicate rows exist

·         Non-clustered indexes are never created in unique key whereas they are created in primary key

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Answered By rahul84 0 points N/A #96811

What is the difference between unique key and primary key?

unique key can contain null value but primary key cannot

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• Posted on - 12/01/2011
• Question Category: MySQL Server