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
Section 3.8: IMPLEMENTATION CONSIDERATIONS*
3.8 IMPLEMENTATION CONSIDERATIONS*
Here we consider subtleties of instants and intervals in specific DBMSs.
3.8.1 IBM DB2 Universal Database
IBM DB2 UDB will generate an error if a field value (e.g., 60 seconds, 24 hours) was out of range. Hence, every minute in DB2 contains exactly 60 seconds; leap seconds are not accommodated.
3.8.2 Microsoft Access
Access interprets the fractional portion of a DATE as a fraction of a day, effectively dividing each day into 86,400 seconds. Hence, every minute in Access contains exactly 60 seconds; Access DATEs do not take into account leap seconds. Access will generate a runtime error if the field value (e.g., 60 seconds, 24 hours) was out of range.
3.8.3 Oracle8 Server
Oracle8 Server date arithmetic takes into account the (Catholic) switch from the Julian to the Gregorian calendar, which eliminated 10 days in October 1582 (October 5 through October 14). Missing dates can be entered into the database, but are ignored in date arithmetic and treated as the next date. For example, the next day after October 4, 1582, is October 15, 1582, and the day following October 5, 1582, is October 15, 1582. Specifically, all the dates between October 5 and October 14 are mapped identically to October 15.
As the maximum number of seconds in a minute in Oracle8 Server is 60, Oracle DATEs do not take into account leap seconds. Instead, Oracle8 Server will generate a runtime error if the field value (e.g., 60 seconds, 24 hours) was out of range.
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