Developing Time-Oriented Database Applications in SQL
An enjoyable plunge into the how-to of time and data, with real-world situations and code.
TABLE OF CONTENTS Developing Time-Oriented Database Applications in SQL
Chapter 3: Instants and Intervals
OVERVIEW
At the core of a temporal application are temporal values, indicating when something happened.There are three basic temporal types. Instants and intervals are covered in this chapter; periods, which enjoy much less support in most versions of SQL, are the topic of the next chapter.
We examine in depth the variants of instants and intervals (SQL-92 supports five instant variants and two interval variants) and the operations permitted on these types. The highly idiosyncratic temporal facilities of prevalent DBMSs are compared in detail with the SQL-92 standard. The language facilities supporting temporal values are similar in one way to assembly language facilities: you can (generally) do what you want, but it is often far from easy.
Jim Barnett is the quintessential Texan: barrel-chested, sporting a thick mustache, a graduate of the University of Texas, an oil man. His speech has an easy cadence, peppered with humor. He is an engineer for GeoQuest, a data management company owned by Schlumberger, a Paris-based instrumentation company. (This name is of Germanic origin, but is pronounced as a French word.)
The oil and gas business is a dynamic, worldwide industry, with its practitioners transferred far and wide, and often. September of 1995 found Jim working in Dubai, U.A.E., 8000 miles from his home base in Houston, Texas, working with the Arabian Oil Company (AOC) to systematize its records on wells and oil and gas production and distribution. Several of his clients are in Al Khafji, a company town immediately south of the Saudi...
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