Notice that some of the properties within the “Product” class are defined as nullable (this is what Decimal? means – that indicates it is a nullable type).  Nullable columns within a database table should be represented within the model class as Nullable properties if they are value types:

You can also optionally omit specifying nullable columns entirely from a model class if you don’t need to access it.  For example, the Product table within Northwind has a “QuantityPerUnit” column that is a nullable nvarchar, and a “UnitsOnOrder” column that is a nullable smallint.  I’ve omitted both of these properties from the “Product” class I defined above.  Because they are nullable within the database I can still retrieve, insert, update and delete Products without problems.