>>In SQL Server you should specify IDENTITY propertry for such column.
>
>In the data type, I the closest one I see if UniqueIdentifier. Is that the one you are referring to? I also assign a primary key on that field but I don't think this is related.

No, it's separate attribute that can be applied to a column with decimal, int, numeric, smallint, bigint, or tinyint data type. There can be only one IDENTITY column per table.