How to Filter the data for the non working days in SQL

Question

I want to filter the data for the non working days. For month December the non working days were the weekends and the days from 20 to 31. Apperantly this (DATEPART (DW, timestamp) IN (1,7 )) AND (DAY(timestamp) between '20' AND '31') does not work since it returns me only the weekends between that range 20 to 31.

Answer 1

Change AND to OR and see what happens.