se nedenstående eksempel
SELECT mydate calendar_date
,EXTRACT(WEEK FROM mydate) week_num
,EXTRACT(month FROM mydate) month_num
,to_char(mydate,'Mon') month_name
,EXTRACT(Quarter FROM mydate) quarter_num
,EXTRACT(year FROM mydate) calendar_year
,EXTRACT(DOW FROM mydate) iso_dayofweek
,to_char(mydate, 'day') dayofweek_name
FROM (
SELECT now()::DATE mydate
) t
Resultat:
calendar_date week_num month_num month_name quarter_num calendar_year iso_dayofweek dayofweek_name
------------- -------- --------- ---------- ----------- ------------- ------------- --------------
2015/04/24 17 4 Apr 2 2015 5 friday
Du kan bruge generate_series() for at få hele datoen på et år, f.eks.:2015
select generate_series(0,364) + date'1/1/2015'
dette vil producere dato fra 1/1/2015 - 31/12/2015 , og brug dette vælg i stedet for SELECT now()::DATE i det givne eksempel
Hvis du vil oprette en tabel for år 2015 så kan du bruge følgende forespørgsel
CREATE TABLE mycal_2015 AS
SELECT row_number() OVER () date_key
,mydate calendar_date
,EXTRACT(WEEK FROM mydate) week_num
,EXTRACT(month FROM mydate) month_num
,to_char(mydate,'Mon') month_name
,EXTRACT(Quarter FROM mydate) quarter_num
,EXTRACT(year FROM mydate) calendar_year
,EXTRACT(DOW FROM mydate) iso_dayofweek
,to_char(mydate, 'day') dayofweek_name
FROM (
SELECT generate_series(0, 364) + DATE '1/1/2015' mydate
) t
og tabellen vil se ud som select * from mycal_2015
date_key calendar_date week_num month_num month_name quarter_num calendar_year iso_dayofweek dayofweek_name
-------- ------------- -------- --------- ---------- ----------- ------------- ------------- --------------
1 2015/01/01 1 1 Jan 1 2015 4 thursday
2 2015/01/02 1 1 Jan 1 2015 5 friday
3 2015/01/03 1 1 Jan 1 2015 6 saturday
4 2015/01/04 1 1 Jan 1 2015 0 sunday
5 2015/01/05 2 1 Jan 1 2015 1 monday
6 2015/01/06 2 1 Jan 1 2015 2 tuesday
...
.
.
.
364 2015/12/30 53 12 Dec 4 2015 3 wednesday
365 2015/12/31 53 12 Dec 4 2015 4 thursday
POSTGRESQL:UDTAG FUNKTION
PostgreSQL-udtræksfunktionen udtrækker dele fra en dato
Syntaks :extract( unit from date )
dato er en dato, et tidsstempel, et klokkeslæt eller en intervalværdi, som datodelen skal udtrækkes fra.
enhed er enhedstypen for intervallet såsom dag, måned, minut, time og så videre
Det kan være en af følgende:
unit description
--------------- -----------------------------------------------------------------------------------------------------------------------------
century Uses the Gregorian calendar where the first century starts at '0001-01-01 00:00:00 AD'
day Day of the month (1 to 31)
decade Year divided by 10
dow Day of the week (0=Sunday, 1=Monday, 2=Tuesday, ... 6=Saturday)
doy Day of the year (1=first day of year, 365/366=last day of the year, depending if it is a leap year)
epoch Number of seconds since '1970-01-01 00:00:00 UTC', if date value. Number of seconds in an interval, if interval value
hour Hour (0 to 23)
isodow Day of the week (1=Monday, 2=Tuesday, 3=Wednesday, ... 7=Sunday)
isoyear ISO 8601 year value (where the year begins on the Monday of the week that contains January 4th)
microseconds Seconds (and fractional seconds) multiplied by 1,000,000
millennium Millennium value
milliseconds Seconds (and fractional seconds) multiplied by 1,000
minute Minute (0 to 59)
month Number for the month (1 to 12), if date value. Number of months (0 to 11), if interval value
quarter Quarter (1 to 4)
second Seconds (and fractional seconds)
timezone Time zone offset from UTC, expressed in seconds
timezone_hour Hour portion of the time zone offset from UTC
timezone_minute Minute portion of the time zone offset from UTC
week Number of the week of the year based on ISO 8601 (where the year begins on the Monday of the week that contains January 4th)
year Year as 4-digits
Bemærk:Udtræksfunktionen gælder for PostgreSQL version 8.4 og nyere
Dato/klokkeslæt funktioner og operatører
generate_series()