select
    case strftime('%w', SALES_DATE)
        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'
    end as WEEK
    ,round(AVG(COUNT)) as AVG_CNT
    ,round(AVG(SALES_AMT))|| '円' as AVG_AMT
from (
select 
    count(*) as COUNT
    ,sum(SALES_AMT) as SALES_AMT
    ,SALES_DATE
from SALES
group by SALES_DATE
)
group by WEEK
order by strftime('%w', SALES_DATE)
;