En dom, 2002-01-06 a 19:01, Gonzalo Paniagua Javier escribio:
> On Fri, Dec 21, 2001 at 12:54:41PM -0300, Juan Andrés Bentancour wrote:
> > I have a postgres table like this:
> >
> > CREATE TABLE "test" ( "timedate" timestamp NOT NULL);
> >
> > INSERT INTO test VALUES ('25/12/2001');
> > INSERT INTO test VALUES ('31/12/2001');
> > INSERT INTO test VALUES ('31/12/2001 23:59:59');
>
> What version of PostgreSQL do you use? It should be above 7.0
> for 'timestamp' to work...
>
select version();
version
-------------------------------------------------------------
PostgreSQL 7.1.2 on i686-pc-linux-gnu, compiled by GCC 2.96
(1 row)
"timestamp" == "datetime" == "timestamp with time zone"
Bye
Juan Andrés
Title: Date/Time Types
3.4. Date/Time TypesPostgres supports the full set of SQL date and time types.
Table 3-6. Date/Time Types
3.4.1. Date/Time InputDate and time input is accepted in almost any reasonable format, including ISO-8601, SQL-compatible, traditional Postgres, and others. The ordering of month and day in date input can be ambiguous, therefore a setting exists to specify how it should be interpreted in ambiguous cases. The command SET DateStyle TO 'US' or SET DateStyle TO 'NonEuropean' specifies the variant "month before day", the command SET DateStyle TO 'European' sets the variant "day before month". The ISO style is the default but this default can be changed at compile time or at run time. See Appendix A for the exact parsing rules of date/time input and for the recognized time zones. Remember that any date or time input needs to be enclosed into single quotes, like text strings. Refer to Section 1.1.2.5 for more information. SQL requires the following syntax type 'value'but Postgres is more flexible. 3.4.1.1. dateThe following are possible inputs for the date type. Table 3-7. Date Input
Table 3-8. Month Abbreviations
3.4.1.2. time [ without time zone ]Per SQL99, this type can be referenced as time and as time without time zone. The following are valid time inputs. 3.4.1.3. time with time zoneThis type is defined by SQL92, but the definition exhibits fundamental deficiencies that render the type nearly useless. In most cases, a combination of date, time, and timestamp should provide a complete range of date/time functionality required by any application. time with time zone accepts all input also legal for the time type, appended with a legal time zone, as follows: Table 3-11. Time With Time Zone Input
Refer to Table 3-12 for more examples of time zones. 3.4.1.4. timestampValid input for the timestamp type consists of a concatenation of a date and a time, followed by an optional AD or BC, followed by an optional time zone. (See below.) Thus 1999-01-08 04:05:06 -8:00
is a valid timestamp value that is ISO-compliant.
In addition, the wide-spread format
January 8 04:05:06 1999 PST
is supported.
3.4.1.5. intervalintervals can be specified with the following syntax: Quantity Unit [Quantity Unit...] [Direction]
@ Quantity Unit [Direction]
where: Quantity is ..., -1,
0, 1, 2, ...;
Unit is second,
minute, hour, day,
week, month, year,
decade, century, millennium,
or abbreviations or plurals of these units;
Direction can be ago or
empty.
3.4.1.6. Special valuesThe following SQL-compatible functions can be used as date or time input for the corresponding data type: CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP. Postgres also supports several special constants for convenience. Table 3-13. Special Date/Time Constants
3.4.2. Date/Time OutputOutput formats can be set to one of the four styles ISO-8601, SQL (Ingres), traditional Postgres, and German, using the SET DateStyle. The default is the ISO format. Table 3-14. Date/Time Output Styles
The output of the date and time styles is of course only the date or time part in accordance with the above examples. The SQL style has European and non-European (US) variants, which determines whether month follows day or vice versa. (See also above at Date/Time Input, how this setting affects interpretation of input values.) Table 3-15. Date Order Conventions
interval output looks like the input format, except that units like week or century are converted to years and days. In ISO mode the output looks like [ Quantity Units [ ... ] ] [ Days ] Hours:Minutes [ ago ] There are several ways to affect the appearance of date/time types:
3.4.3. Time ZonesPostgres endeavors to be compatible with SQL92 definitions for typical usage. However, the SQL92 standard has an odd mix of date and time types and capabilities. Two obvious problems are:
To address these difficulties, we recommend using date/time types that contain both date and time when using time zones. We recommend not using the SQL92 type TIME WITH TIME ZONE (though it is supported by Postgres for legacy applications and for compatibility with other RDBMS implementations). Postgres assumes local time for any type containing only date or time. Further, time zone support is derived from the underlying operating system time zone capabilities, and hence can handle daylight savings time and other expected behavior. Postgres obtains time zone support from the underlying operating system for dates between 1902 and 2038 (near the typical date limits for Unix-style systems). Outside of this range, all dates are assumed to be specified and used in Universal Coordinated Time (UTC). All dates and times are stored internally in UTC, traditionally known as Greenwich Mean Time (GMT). Times are converted to local time on the database server before being sent to the client frontend, hence by default are in the server time zone. There are several ways to affect the time zone behavior:
3.4.4. InternalsPostgres uses Julian dates for all date/time calculations. They have the nice property of correctly predicting/calculating any date more recent than 4713BC to far into the future, using the assumption that the length of the year is 365.2425 days. Date conventions before the 19th century make for interesting reading, but are not consistent enough to warrant coding into a date/time handler. |