SQL Server auto increment a column without primary key

Question

Is it possible to auto increment a column in SQL Server WITHOUT it being a primary key?

If yes how can this be done.

Thanks

Answer 1

Declare the column with the IDENTITY keyword, and simply do not create a PRIMARY KEY constraint on it.

Answer 2

Yes. There is no requirement that IDENTITY columns be made a primary key.

CREATE TABLE T
(
X INT PRIMARY KEY,
Y INT IDENTITY(1,1)
)

Though I'm not sure when this would be useful. If you have a natural key that you want to use as the PK then you would probably want to put a unique constraint on the surrogate alternate key anyway.

For purposes of setting up FK relationships SQL Server doesn't care if the column(s) is the PK or not it just requires a unique index on it/them.