Posted by Erland Sommarskog on 11/26/07 22:21

Tony Rogerson (tonyrogerson@torver.net) writes:
>> 1) NULL-able
>> 2) More than one column can have the same data type
>> 3) Has to take CHECK() constraints
>> 4) Appropriate computations can done on it (numeric, string or
>> temporal)
>
>> IDENTITY has none of the properties of a data type because it is not a
>> data type at all.
>...
> The column that has the IDENTITY property can have all the aspects you
> speek of - you are compeltely wrong.

Sorry, Tony, but sometimes Joe is right. An IDENTITY column cannot be
nullable, and you can only have one of them in a table. Not that see
any practical importance of this.

--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server 2005 at
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