WITH RECURSIVE
cnt(x) AS (VALUES(julianday(replace('2022/08/01', '/', '-') ))
UNION ALL
SELECT x+1 FROM cnt WHERE x < julianday(replace('2022/09/01', '/', '-') ))

select strftime('%Y-%m-%d', c.x) as REGIST_DATE,
case strftime('%w', CONFIRMED_AT)
when '0' then '日'
when '1' then '月'
when '2' then '火'
when '3' then '水'
when '4' then '木'
when '5' then '金'
when '6' then '土'
else 'undefined'
end as WK,
from cnt JOIN (
select strftime('%Y-%m-%d', CONFIRMED_AT) as REGIST_DATE,
case strftime('%w', CONFIRMED_AT)
when '0' then '日'
when '1' then '月'
when '2' then '火'
when '3' then '水'
when '4' then '木'
when '5' then '金'
when '6' then '土'
else 'undefined'
end as WK,
COUNT(*) as TOTAL
from USERS
where VALID_FLG	= 1 
and CONFIRMED_AT >= '2022-08-01' AND CONFIRMED_AT <= '2022-08-31'
group by REGIST_DATE
) on