Databases that serve business applications often need to support temporal data. For example, suppose a contract with a supplier is valid for a limited time only. It could be valid from a specific point in time onward, or it could be valid for a specific time interval—from a starting time point to an ending time point. In addition, often you'll need to audit all changes in one or more tables. You might also need to be able to show the state at a specific point in time, or all changes made to a table in a specific period of time. From a data integrity perspective, you might need to implement many additional temporal-specific constraints.
This chapter introduces temporal problems, deals with manual solutions, and shows you out-of-the-box ...
