Applicability Period

Definition

The applicability period (or period of applicability) for a modification (generally an insertion, deletion, or update) is the time period that modification is to be applied. Generally the modification is a sequenced modification and the period applies to valid time. This period should be distinguished from lifespan.

Key Points

The applicability period is specified within a modification statement. In constrast, the lifespan is an aspect of a stored fact.

This illustration uses the TSQL2 language, which has an explicit VALID clause to specify the applicability period within an INSERT, DELETE, or UPDATE statement.

For insertions, the applicability period is the valid time of the fact being inserted. The following states that Ben is in the book department for 1 month in 2007.

• INSERT INTO EMPLOYEE

• VALUES (‘Ben’, ‘Book’)

• VALID PERIOD ‘[15 Feb 2007, 15 Mar 2007]’

For a deletion, the applicability period states for what period of time the deletion is to be applied. The following...