Populating a table with all dates in a given range in Google BigQuery

Question

Is there any convenient way to populate a table with all dates in a given range in Google BigQuery? What I need are all dates from 2015-06-01 till CURRENT_DATE(), so somethi

Answer 1

Mikhail's answer works for BigQuery's legacy sql syntax perfectly. This solution is a slightly easier one if you're using the standard SQL syntax.

BigQuery standard SQL syntax actually has a built in function, GENERATE_DATE_ARRAY for creating an array from a date range. It takes a start date, end date and INTERVAL. For example:

SELECT day
FROM UNNEST(
    GENERATE_DATE_ARRAY(DATE('2015-06-01'), CURRENT_DATE(), INTERVAL 1 DAY)
) AS day

If you wanted the week and year you could use

SELECT EXTRACT(YEAR FROM day), EXTRACT(WEEK FROM day)
FROM UNNEST(
    GENERATE_DATE_ARRAY(DATE('2015-06-01'), CURRENT_DATE(), INTERVAL 1 WEEK)
) AS day

Answer 2

all dates from 2015-06-01 till CURRENT_DATE()

SELECT DATE(DATE_ADD(TIMESTAMP("2015-06-01"), pos - 1, "DAY")) AS DAY
FROM (
     SELECT ROW_NUMBER() OVER() AS pos, *
     FROM (FLATTEN((
     SELECT SPLIT(RPAD('', 1 + DATEDIFF(TIMESTAMP(CURRENT_DATE()), TIMESTAMP("2015-06-01")), '.'),'') AS h
     FROM (SELECT NULL)),h
)))

all weeks between the two dates

SELECT YEAR(DAY) AS y, WEEK(DAY) AS w
FROM (
  SELECT DATE(DATE_ADD(TIMESTAMP("2015-06-01"), pos - 1, "DAY")) AS DAY
  FROM (
       SELECT ROW_NUMBER() OVER() AS pos, *
       FROM (FLATTEN((
       SELECT SPLIT(RPAD('', 1 + DATEDIFF(TIMESTAMP(CURRENT_DATE()), TIMESTAMP("2015-06-01")), '.'),'') AS h
       FROM (SELECT NULL)),h
  )))
)
GROUP BY y, w