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Are you supposed to apply the primary key to an IDENTITY column? Please elaborate.

Posted on 2013-02-07
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When creating  an IDENTITY column in  a table do you also apply a primary key to it?


Example:
CREATE TABLE HR.Employees(
EmployeeId INT IDENTITY(1000 ,2) NOT NULL
,etc…)
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Question by:rhservan
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Jim Horn earned 2000 total points
ID: 38865555
Identity fields are almost always primary keys yes, as it guarantees uniqueness in a row, but it is not required.

In your above T-SQL, making EmployeID the identity field might not always work, if the client sees a scenario where they would want to manually change the id for whatever reason.   If that's the case, an identity field would be the primary key, the actual EmployeeID would be what's called a 'business key'.  Forms would always display business key, and the database is related via the identity field.

You'll have to feel them out on that one.
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LVL 66

Expert Comment

by:Jim Horn
ID: 38865687
Thanks for the grade.  Good luck with your project.  -Jim
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