Temporal upward compatibility
Current semantics constrains the semantics of non-temporal statements applied to temporal databases. Specifically, current semantics requires that non-temporal statements behave as if applied to the non-temporal database that is the result of taking the timeslice of the temporal database at the current time.
Current semantics  requires that queries and views on a temporal database consider the current information only and work exactly as if applied to a non-temporal database. For example, a query to determine who manages the high-salaried employees should consider the current database state only. Constraints and assertions also work exactly as before: they are applied to the current state and checked on database modification.
Database modifications are subject to the same constraint as queries: they should work exactly as if applied to a non-temporal database. Database modifications, however, also have to take into...
- 1.Bair J, Böhlen MH, Jensen CS, Snodgrass RT. Notions of upward compatibility of temporal query languages. Wirtschaftsinformatik. 1997;39(1):25–34.Google Scholar
- 4.Melton J, editor. ISO/IEC 9075, database language SQL:2011 Part 2: SQL/foundation, Dec 2011.Google Scholar
- 5.Snodgrass RT. Developing time-oriented database applications in SQL. San Francisco: Morgan Kaufmann; 1999.Google Scholar