Parsing Date time in BigQuery

Question

Below is the date format for the 'date' field, which I'm getting from API to Bigquery as a string. 2020-09-17T00:00:00+03:00 I want to parse the date format to '%Y%m%d' and then extract it as ISOWEEK. This is the code I came up with;

EXTRACT(ISOWEEK FROM PARSE_DATETIME("%Y%m%d", REGEXP_EXTRACT(date, r"...................")))

However, this gives me an error. Could you guide me what needs change? Thank you

Answer 1

Let's break down the steps here. The date input is a string of a date in a certain timezone (+03:00), for example "2020-09-17T00:00:00+03:00" . Then on this string you can apply:

• Keep the date on the correct timezone

DATE("2020-09-17T00:00:00+03:00", "+03:00")

• Format the date with the desired format in a string

FORMAT_DATE("%Y/%m/%d", DATE("2020-09-17T00:00:00+03:00", "+03:00"))

• Parse the date from the previously formatted string

PARSE_DATE("%Y/%m/%d", FORMAT_DATE("%Y/%m/%d", DATE("2020-09-17T00:00:00+03:00", "+03:00")))

• Finally extract the ISOWEEK from the date

EXTRACT(ISOWEEK FROM PARSE_DATE("%Y/%m/%d", FORMAT_DATE("%Y/%m/%d", DATE("2020-09-17T00:00:00+03:00", "+03:00"))))

So, this will give you the result you want.

select EXTRACT(ISOWEEK FROM PARSE_DATE("%Y/%m/%d", FORMAT_DATE("%Y/%m/%d", DATE(date))))

You can also skip the "%Y/%m/%d" if it's not really helping you with something else and simply do

select EXTRACT(ISOWEEK FROM DATE("2020-09-17T00:00:00+03:00", "+03:00"))

which results to the same thing