Getting week of the month. Week should start on Monday and end a Sunday - sql

Question

I need to add new business wee to my dim_date actually i have week of the month that is counting every 7 days of month as the table bellow.
Date
Week of month
day_of_week
01/04/2022
1
Friday
02/04/2022
1
Saturday
03/04/2022
1
Sunday
04/04/2022
1
Monday
05/04/2022
1
Tuesday
06/04/2022
1
Wednesday
07/04/2022
1
Thursday
08/04/2022
2
Friday
09/04/2022
2
Saturday
10/04/2022
2
Sunday
But for this business week column the week should start on Monday and end at Sunday, even if the first week is only one day(when a month starts at Sunday), but if the month starts on Friday, I should consider it as the first week of the month.
Date
Week of month
day_of_week
01/04/2022
1
Friday
02/04/2022
1
Saturday
03/04/2022
1
Sunday
04/04/2022
2
Monday
05/04/2022
2
Tuesday
06/04/2022
2
Wednesday
07/04/2022
2
Thursday
08/04/2022
2
Friday
09/04/2022
2
Saturday
10/04/2022
2
Sunday
Do you have any suggestion to calculate this?
Thank you

Answer 1

This query gets the number of the week from 2002-04-01 to 2002-04-19. The week start from monday and finishes on sunday. You can see this example:
with sample_data as (
SELECT date FROM UNNEST(generate_timestamp_array('2022-04-01', '2022-04-19', INTERVAL 1 DAY)) as date
)
select
date
, extract(week(MONDAY) from date)-(extract(MONTh from date)-1)*4 AS days_diff
, FORMAT_DATE('%A', date)
from sample_data
You can see the result.
You need to use EXTRACT function.

Answer 2

i hope that this solution i figured out could help you in the future or we can discuss and imporve this solution:
WITH sample_data AS (SELECT
date,
EXTRACT(WEEK FROM date) AS week_of_year,
DATE_TRUNC(date, MONTH) AS FIRST_DAY_OF_MONTH
FROM (SELECT date
FROM UNNEST(GENERATE_TIMESTAMP_ARRAY('2022-04-01', '2022-04-19', INTERVAL 1 DAY)) AS date))
SELECT
date,
FORMAT_DATE('%A', date) as day_name,
CASE
WHEN CAST(EXTRACT(WEEK(MONDAY) FROM d.date) AS INT) = 0 AND d.WEEK_OF_YEAR IN (52, 53) THEN 1
WHEN CAST(EXTRACT(WEEK(MONDAY) FROM d.FIRST_DAY_OF_MONTH) AS INT) = 0 THEN EXTRACT(WEEK(MONDAY) FROM d.date) + 1
ELSE (d.WEEK_OF_YEAR - CAST(EXTRACT(WEEK(MONDAY) FROM d.FIRST_DAY_OF_MONTH) AS INT)) + 1
END AS BUSINESS_WEEK_OF_MONTH
FROM sample_data d;