Modeling and Storage Principles
In the past, conventional database principles were used, meaning only currently valid states were in operation and manipulated with no specification of their period of validity. Therefore, date and time values were significantly limited. Nowadays, the situation is different. One aspect of current information systems is state monitoring over time, and another is the length of time that the state is valid. For example, an employment contract specifies the time frame that it is valid, within which the employee is expected to be available and attend to their duties, as well as noting their activities, responsibilities, and so on. If the employee leaves the company, they should automatically lose access to the information systems or data storage repositories. However, data about the employee cannot be removed as many references to it exist. The history of the assignments and responsibilities must be stored. Another example is webshop registration. Even if...