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hur man skapar ISO-8601 gregoriansk datumtabell i postgres

se exemplet nedan

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 använda generate_series() för att få alla datum på ett år till exempel:2015

select generate_series(0,364) + date'1/1/2015'

detta kommer att producera datum från 1/1/2015 - 31/12/2015 , och använd detta val istället för SELECT now()::DATE i det givna exemplet

Om du vill skapa tabell för år 2015 sedan kan du använda följande fråga

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

och tabellen kommer att se ut 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:EXTRAHERA FUNKTION

PostgreSQL-extraktfunktionen extraherar delar från ett datum

Syntax :extract( unit from date )

datum är ett datum, tidsstämpel, tid eller intervallvärde från vilket datumdelen ska extraheras.

enhet är enhetstypen för intervallet som dag, månad, minut, timme och så vidare

Det kan vara något av följande:

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                                                                                                             

Obs:Extract-funktionen gäller för PostgreSQL version 8.4 och senare

Datum/tid-funktioner och operatörer
generate_series()




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