Oracle 如何将日期转换为周数

我需要每周做报告，但我的周数应该从每月的第一天开始

以下是我的示例数据：

report_date  Vol 
01 nov 2014   23
03 nov 2014   34
16 nov 2014   56
30 nov 2014   44

期望输出

Week no  Vol
1         57
2         56
3         0
4         44

希望它清楚

谢谢

select to_char(report_date, 'W'), sum(vol)
from your_table
group by to_char(report_date, 'W');

W每月的第1周（1-5），其中第1周从每月的第一天开始 本月7日结束

---

由于您期望的输出也包括“零”行，并且假设您希望此报告也能跨多个月工作：

WITH sample_data AS
  (SELECT DATE '2014-11-01' AS report_date, 23 AS vol FROM DUAL
UNION ALL SELECT DATE '2014-11-03', 34 FROM DUAL
UNION ALL SELECT DATE '2014-11-16', 56 FROM DUAL
UNION ALL SELECT DATE '2014-11-30', 44 FROM DUAL)
 ,weeks AS
  (SELECT report_month
         ,TO_CHAR(ROWNUM) AS week_no
   FROM   (SELECT DISTINCT
                  TRUNC(report_date,'MM') AS report_month
           FROM   sample_data)
   CONNECT BY LEVEL <= TO_NUMBER(TO_CHAR(LAST_DAY(report_month),'W')))
SELECT TO_CHAR(weeks.report_month,'Month') AS "Month"
      ,weeks.week_no AS "Week no"
      ,NVL(sum(sample_data.vol),0) AS "Vol"
FROM   weeks
LEFT JOIN sample_data
ON     weeks.report_month = TRUNC(report_date,'MM')
AND    weeks.week_no = to_char(report_date,'W')
GROUP BY weeks.report_month, weeks.week_no ORDER BY 1,2;

---

几乎是：他想在空的几周里得到0

Month    Week no Vol
======== ======= ===
November 1        57
November 2         0
November 3        56
November 4         0
November 5        44