Handling Temporal Data
IN THIS CHAPTER
Defining times and periods
Tracking what happened at specific times
Providing an audit trail of changes to the data
Handling both what happened and when the event was recorded
Formatting and parsing dates and times
Before SQL:2011, ISO/IEC standard SQL had no mechanism for dealing with data that was valid at one point in time but not valid at another. Any application that requires that an audit trail be kept needs that capability. This means that the burden of keeping track of what was true at a given time falls on the application programmer rather than the database. This sounds like a recipe for complicated, over-budget, late, and bug-infested applications.
Syntax was added to SQL:2011 that enables handling of temporal data without messing up the way code for non-temporal data is handled. This is a big advantage for anyone who wants to add temporal capability to an existing SQL database. Even though SQL:2011 standardized how to handle ...