Chapter 7

Handling Temporal Data

In This Chapter

arrow Defining times and periods

arrow Tracking what happened at specific times

arrow Providing an audit trail of changes to the data

arrow Handling both what happened and when the event was recorded

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.

New syntax has been added to SQL:2011 that enables handling of temporal data without messing up the way code for nontemporal data is handled. This is a big advantage for anyone who wants to add temporal capability to an existing SQL database.

What do I mean by the term temporal data? The ISO/IEC SQL:2011 standard does not use that term at all, but it is commonly used in the database community. In SQL:2011, temporal ...

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