identity columns store sequential numbers (such as invoice numbers, employee numbers, or record numbers) that are generated automatically. The value of the identity column uniquely identifies each row in a table.
identity columns use the numeric underlying datatype with scale 0, between 1 and 1038 -1, inclusive.
identity columns are never updated by the update command. update applied to primary data from a replicate site (using a request function) can never update the identity column with identity data.
