generate_series() equivalent in snowflake

问题

I'm trying to find the snowflake equivalent of generate_series() (the PostgreSQL syntax).

SELECT generate_series(timestamp '2017-11-01', CURRENT_DATE, '1 day')

回答1:

This is how I was able to generate a series of dates in Snowflake. I set row count to 1095 to get 3 years worth of dates, you can of course change that to whatever suits your use case

select 
    dateadd(day, '-' || seq4(), current_date()) as dte 
from 
    table 
       (generator(rowcount => 1095))

Originally found here

EDIT: This solution is not correct. seq4 does not guarantee a sequence without gaps. Please follow other answers, not this one. Thanks @Marcin Zukowski for pointing that out.

回答2:

Just wanted to expand on Marcin Zukowski's comment to say that these gaps started to show up almost immediately after using a date range generated this way in a JOIN.

We ultimately ended up doing this instead!

select
  dateadd(
    day,
    '-' || row_number() over (order by null),
    dateadd(day, '+1', current_date())
  ) as date
from table (generator(rowcount => 90))

回答3:

I had a similar problem and found an approach, which avoids the issue of a generator requiring a constant value by using a session variable in addition to the already great answers here. This is closest to the requirement of the OP to my mind.

-- set parameter to be used as generator "constant" including the start day
set num_days =  (Select datediff(day, TO_DATE('2017-11-01','YYYY-MM-DD'), current_date()+1));
-- use parameter in bcrowell's answer now
select
  dateadd(
    day,
    '-' || row_number() over (order by null),
    dateadd(day, '+1', current_date())
  ) as date
from table (generator(rowcount => ($num_days)));
-- clean up previously set variable
unset num_days;

来源：https://stackoverflow.com/questions/54348801/generate-series-equivalent-in-snowflake

标签

sql

generate-series

snowflake-cloud-data-platform