WITH T AS(
    SELECT '2011-01-01' DAY,10 CNT FROM DUAL UNION ALL
    SELECT '2011-01-02' DAY,42 FROM DUAL UNION ALL
    SELECT '2011-01-03' DAY,13 FROM DUAL UNION ALL
    SELECT '2011-01-07' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-08' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-09' DAY,2 FROM DUAL UNION ALL
    SELECT '2011-01-10' DAY,3 FROM DUAL UNION ALL
    SELECT '2011-01-11' DAY,13 FROM DUAL UNION ALL
    SELECT '2011-01-12' DAY,1 FROM DUAL UNION ALL
    SELECT '2011-01-13' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-14' DAY,1 FROM DUAL UNION ALL
    SELECT '2011-01-15' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-19' DAY,2 FROM DUAL UNION ALL
    SELECT '2011-01-20' DAY,3 FROM DUAL UNION ALL
    SELECT '2011-01-21' DAY,4 FROM DUAL
)
SELECT DAY,RESULT
FROM
(
    SELECT DAY,CNT
    ,TO_CHAR(TO_DATE(DAY,'YYYY-MM-DD'),'D') YOIL
    ,SUM(CNT) OVER(PARTITION BY TO_CHAR(TO_DATE(DAY,'YYYY-MM-DD'),'WW')) RESULT
    FROM T
)
WHERE YOIL = 6
ORDER BY DAY

WITH T AS(
    SELECT '2011-01-01' DAY,10 CNT FROM DUAL UNION ALL
    SELECT '2011-01-02' DAY,42 FROM DUAL UNION ALL
    SELECT '2011-01-03' DAY,13 FROM DUAL UNION ALL
    SELECT '2011-01-07' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-08' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-09' DAY,2 FROM DUAL UNION ALL
    SELECT '2011-01-10' DAY,3 FROM DUAL UNION ALL
    SELECT '2011-01-11' DAY,13 FROM DUAL UNION ALL
    SELECT '2011-01-12' DAY,1 FROM DUAL UNION ALL
    SELECT '2011-01-13' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-14' DAY,1 FROM DUAL UNION ALL
    SELECT '2011-01-15' DAY,5 FROM DUAL UNION ALL
    SELECT '2011-01-19' DAY,2 FROM DUAL UNION ALL
    SELECT '2011-01-20' DAY,3 FROM DUAL UNION ALL
    SELECT '2011-01-21' DAY,4 FROM DUAL
)
select max(day) max_day,sum(cnt) cnt
from t
group by to_char(to_date(day,'yyyy-mm-dd')+2,'yyyy'),
         to_char(to_date(day,'yyyy-mm-dd')+2,'iw')
order by max_day