From "Using the Entity Classes" in the documentation.
Self servicing
The code is aware of sequences / identity columns and will automatically set the value for an identity / sequence column right after the Save() method returns, thus is available in the next statement after a call to Save(). If you're using a database which uses sequences, like Oracle or Firebird, be sure to define the field which should be used with a sequence as identity in the entity editor.
Adapter
The code is aware of sequences / identity columns and will automatically set the value for an identity / sequence column after the entity is physically saved inside SaveEntity(). The new value for sequenced columns is available to you after SaveEntity(), even though you haven't specified that the entity has to be refetched. This can be helpful if you want to refetch the entity later. If you're using a database which uses sequences, like Oracle or Firebird, be sure to define the field which should be used with a sequence as identity in the entity editor. Because the entity saved is new (customer.IsNew is true), SaveEntity() will use an INSERT query. After a successful save, the IsNew flag is set to false and the State property of the Fields object of the saved entity is set to EntityState.Fetched (if the entity is also refetched) or EntityState.OutOfSync.
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