按周分组统计

SELECT sunday||'~'||saturday AS weekday,staff_name,SUM(effort) sum
FROM (
SELECT CASE
WHEN to_char(work_date,'D')=1 THEN
     to_char(trunc(work_date-7-1),'YYYY-MM-DD')
ELSE
     to_char(trunc(next_day(work_date,2)-7-1),'YYYY-MM-DD')
END AS sunday,
CASE
WHEN to_char(work_date,'D')=1 THEN
     to_char(trunc(work_date-1),'YYYY-MM-DD')
ELSE
     to_char(trunc(next_day(work_date,1)-1),'YYYY-MM-DD')
ENDAS saturday,staff_info.staff_name staff_name,effort
FROM task_info,staff_info
where Task_Info.Staff_Sril=staff_info.staff_sril
      and work_date >= to_date('2007-04-01','yyyy-mm-dd')
      and work_date<=to_date('2007-05-06','yyyy-mm-dd')
)
GROUP BY cube(sunday||'~'||saturday,staff_name)