Non-key columns can be included in non-clustered index to avoid exceeding the current index size limitations of a maximum of 16 key columns and a maximum index key size of 900 bytes.
Another advantage is that using non-key column in index we can have index data types not allowed as index key columns generally.
Non-key columns can be included only in non-clustered indexes.
Columns can’t be defined in both the key column and they INCLUDE list.
Cookies are the best way to store state data that must be available for multiple Web pages on a web site. Query Strings – Query strings store values in the URL that are visible to the user. Application State – Application State information is available to all pages, regardless of which user requests a page. Session State – Session State information is available to all pages opened by a user during a single visit.
Use query strings when you want a user to be able to e-mail or instant message state data with a URL. Both application state and session state information is lost when the application restarts.
Immutable means once we created we cannot modified.Column names can’t be repeated in the INCLUDE list.Non-key columns can be dropped from a table only after the non-key index is dropped first.To persist user data between application restarts, you can store it using profile properties.Abstract class is a class which can’t be instantiate.