Bruno Wolff III wrote:
Shouldn't you be using 365.2425/12 (30.436875) for the number of days per month?
Well, ISO 8601 prefers "30" to some weird fraction when they define the term "month"; and uses a different term "calendar month" for the exact number of days in a known month. They make a similar distinction between "day" which is defined as "24 hours" and "calendar day" which includes leap seconds, locally inserted & deleted daylight savings time hours, etc. None of this really matters because the SQL standard only chose to import a couple definitions from ISO 8601 which do not include "month" or "day". But regarding the naming; it would be consistent with iso 8601 if people wanted to make a distinction between "months" and "calendar months". http://lists.ebxml.org/archives/ebxml-core/200104/pdf00005.pdf " 3.15 month unit of time of 28, 29, 30 or 31 days NOTE In certain applications a month is regarded as a unit of time of 30 days. 3.16 month, calendar time-interval resulting from the division of a calendar year in 12 sequential time-intervals, each with a specific name and containing a specified number of calendar days 3.6 day unit of time of 24 hours 3.7 day, calendar time-interval starting at [0000] and ending at [2400] (which is equal to the beginning of the next calendar day); typically a calendar day has a duration of 24 h [...] NOTE 2 The duration of a calendar day is 24 hours; except if modified by: — the insertion or deletion of leap seconds, by decision of the IERS, or — the insertion or deletion of other time intervals, as may be prescribed by local authorities to alter local time. " ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
