分组补空值问题

来源：互联网发布：caffe 预处理编辑：程序博客网时间：2024/06/05 10:31

http://topic.csdn.net/u/20110722/15/14f831ce-bb72-44c9-b0be-70d1ba0bf6a2.html?81007

我测试通过的sql
SELECT TO_CHAR(DAYOFMONTH, 'yyyy-mm-dd'), NVL(sum(b), 0)
FROM tb
RIGHT JOIN (SELECT SYSDATE - (LEVEL - 1) AS DAYOFMONTH
FROM DUAL
CONNECT BY LEVEL <= 60) ON TO_CHAR(time, 'yyyy-mm-dd') = TO_CHAR(DAYOFMONTH,'yyyy-mm-dd')
where DAYOFMONTH >= TO_DATE('2011-07-01','yyyy-mm-dd')
GROUP BY TO_CHAR(DAYOFMONTH, 'yyyy-mm-dd')
ORDER BY TO_CHAR(DAYOFMONTH, 'yyyy-mm-dd') ASC

输出
2011-07-01 0
2011-07-02 0
2011-07-03 0
2011-07-04 12
……
2011-07-14 13
……

CREATE TABLE TB
(
A     INTEGER,
B     INTEGER,
C     INTEGER,
TIME DATE
)

http://topic.csdn.net/u/20110721/17/913972e9-4c21-4c42-8517-8266760f94c1.html
我测试通过的sql
with t1 as(
select '2011-'||lpad(level,2,0) a
    from dual connect by level <= 12
)select t1.a,nvl(sum(t2.num),0)
   from tb2 t2
   RIGHT JOIN t1 on t1.a = to_char(t2.curdate,'yyyy-mm')
group by t1.a;

结果
2011-01 0
2011-02 20
2011-03 0
2011-04 20
……
2011-06 70
……

CREATE TABLE TB2
(
ID INTEGER,
CURDATE DATE,
NUM INTEGER
)