The Data Model for Time

TSQL2 adds comprehensive support for time to SQL-92. This support rests on three temporal dimensions: user-defined time, valid time, and transaction time. A single model of time, however, is the foundation for each of these separate dimensions. In this chapter, we present TSQL2’s model of time. We focus on the concepts of an instant and a period, discuss how each is modeled in TSQL2, and give an overview of the semantics of operations on the modeled entities.