how to create ISO-8601 gregorian date table in pos

Question

I'm looking to create a date table in a postgres database. The sample data is expected to look like this:

date key = 00001
calendar_date= 1/1/2015
week_num= 1
month_num= 1
month_name= Jan
quarter_num= 1
calendar_year= 2015
iso_dayofweek= 4
dayofweek_name= Thursday

Is there a function or SQL that I can get help with to create a date gregorian ISO-8601 table?
I am looking to auto generate this if possible. Any help in this direction would be appreciated.

Answer 1

see the below example

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

Result:

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       

You can use generate_series() to get all date in a year for ex: 2015

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

this will produce date from 1/1/2015 - 31/12/2015, and use this select instead of SELECT now()::DATE in the given example

If you want to create table for year 2015 then you can use the following query

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

and the table will look like 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: EXTRACT FUNCTION

The PostgreSQL extract function extracts parts from a date

Syntax : extract( unit from date )

date is a date, timestamp, time, or interval value from which the date part is to be extracted.

unit is the unit type of the interval such as day, month, minute, hour, and so on

It can be one of the following:

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                                                                                                             

Note: Extract function is applies to PostgreSQL version 8.4 and above

Date/Time Functions and Operators
generate_series()