Time-Dependent Key Components
The key of some views can be divided into a non-time-dependent and a time-dependent component. The records of these views have a time-dependent meaning. This is explained in the example below.
The prices of services change depending on the date. A view contains the service code, a date field and a field for the price. The field for the service code is the non-time-dependent component of the key and the field for the date is the time-dependent component of the key.
If you select maintenance status read and change (time-dependent views) for the view, only records that have the same service code as existing records can be inserted with the view. You can also enter a new price for an existing service as of a new date. You can insert records only if they already have a service code. New services cannot be inserted with the view. You can see this in the figure below.
