我有一个Mview，可以按idNumber和Month提供数据分组。所以如果没有特定月份的数据，我想显示0。这是我的问题：
select MonthName, myCost, myNumber
from
(
select MONTH mm, myCost, myNumber
from myOracle_mv
) myTotals,
(
select to_char(date '2012-12-1' + numtoyminterval(level,'month'), 'mm') MonthName
from dual
connect by level <= 12
) ALLMONTHS
where mm = MonthName
所以我期待：
Month Number Data
-----------------------
1 abc123 4444
2 0
3 abc123 4444
4 abc123 4444
5 0
6 abc123 4444
7 abc123 4444
8 0
9 abc123 4444
10 abc123 4444
11 0
12 abc123 4444
相反，我仍然得到：
1 abc123 4444
3 abc123 4444
4 abc123 4444
6 abc123 4444
7 abc123 4444
9 abc123 4444
10 abc123 4444
12 abc123 4444
有什么想法吗？
谢谢！
编辑：谢谢你的回答。我确实在我的查询中有外部联接但忘记输入，因为集中于更改表/列的名称。
所以是的，我尝试过OUTER JOIN，但仍然没有得到预期的结果。非常感谢任何反馈。
编辑：这是myOracle_MV上的数据：
3777.24 AAA 1 2012
49973.12 AAA 2 2012
4049.91 AAA 3 2012
469.485 AAA 4 2012
5872.22 AAA 5 2012
65837.71 AAA 6 2012
566.23 AAA 7 2012
18432.95 AAA 8 2012
4337.75 AAA 12 2011
18811 BBB 1 2012
29872.67 BBB 2 2012
29068.55 BBB 3 2012
264957.8 BBB 4 2012
67673 BBB 5 2012
855.02 BBB 6 2012
5226.1 BBB 7 2012
2663.24 BBB 8 2012
5490.58 BBB 12 2011
3845.47 CCC 1 2012
3050.54 CCC 2 2012
3784.44 CCC 3 2012
799.73 CCC 4 2012
124884.2 CCC 5 2012
5157.24 CCC 6 2012
19184.78 CCC 7 2012
2280.05 CCC 8 2012
107.07 DDD 3 2012
181.78 DDD 4 2012
110.09 DDD 5 2012
18016.19 DDD 6 2012
1772.95 DDD 7 2012
63.32 DDD 8 2012
答案 0 :(得分：5)
与现有答案非常相似，但是：
select months.month, mv.mycost, coalesce(mv.mynumber, 0) as mynumber
from (
select to_char(date '1970-01-01'
+ numtoyminterval(level - 1, 'month'), 'mm') as month
from dual
connect by level <= 12) months
left join myoracle_mv mv
on mv.month = months.month
order by months.month, mv.mycost, mv.mynumber;
给出了您发布的数据：
MONTH MYCOST MYNUMBER
----- ------ ----------
01 AAA 3777.24
01 BBB 18811
01 CCC 3845.47
02 AAA 49973.12
02 BBB 29872.67
02 CCC 3050.54
03 AAA 4049.91
03 BBB 29068.55
03 CCC 3784.44
03 DDD 107.07
04 AAA 469.485
04 BBB 264957.8
04 CCC 799.73
04 DDD 181.78
05 AAA 5872.22
05 BBB 67673
05 CCC 124884.2
05 DDD 110.09
06 AAA 65837.71
06 BBB 855.02
06 CCC 5157.24
06 DDD 18016.19
07 AAA 566.23
07 BBB 5226.1
07 CCC 19184.78
07 DDD 1772.95
08 AAA 18432.95
08 BBB 2663.24
08 CCC 2280.05
08 DDD 63.32
09 0
10 0
11 0
12 AAA 4337.75
12 BBB 5490.58
35 rows selected
如果您想在mynumber列中显示零，那么您可以这样做：
select months.month, mv.mycost, coalesce(mv.mynumber, 0) as mynumber
给出：
...
08 DDD 63.32
09 0
10 0
11 0
12 AAA 4337.75
...
根据对Jafar回答的评论，听起来好像你自己已经走得那么远，但是对于所有月份的所有mycost值，你想要零值。如果是这种情况，那么您需要获取mycost和外部联接的可能值列表。这将获取MV中的所有值：
select months.month, costs.mycost, coalesce(mv.mynumber, 0) as mynumber
from (
select to_char(date '1970-01-01'
+ numtoyminterval(level - 1, 'month'), 'mm') as month
from dual
connect by level <= 12) months
cross join (
select distinct mycost
from myoracle_mv) costs
left join myoracle_mv mv
on mv.month = months.month
and mv.mycost = costs.mycost
order by months.month, costs.mycost, mv.mynumber;
并给出：
MONTH MYCOST MYNUMBER
----- ------ ----------
01 AAA 3777.24
01 BBB 18811
01 CCC 3845.47
01 DDD 0
02 AAA 49973.12
02 BBB 29872.67
02 CCC 3050.54
02 DDD 0
03 AAA 4049.91
03 BBB 29068.55
03 CCC 3784.44
03 DDD 107.07
04 AAA 469.485
04 BBB 264957.8
04 CCC 799.73
04 DDD 181.78
05 AAA 5872.22
05 BBB 67673
05 CCC 124884.2
05 DDD 110.09
06 AAA 65837.71
06 BBB 855.02
06 CCC 5157.24
06 DDD 18016.19
07 AAA 566.23
07 BBB 5226.1
07 CCC 19184.78
07 DDD 1772.95
08 AAA 18432.95
08 BBB 2663.24
08 CCC 2280.05
08 DDD 63.32
09 AAA 0
09 BBB 0
09 CCC 0
09 DDD 0
10 AAA 0
10 BBB 0
10 CCC 0
10 DDD 0
11 AAA 0
11 BBB 0
11 CCC 0
11 DDD 0
12 AAA 4337.75
12 BBB 5490.58
12 CCC 0
12 DDD 0
48 rows selected
但希望你有另一个表格，其中包含可能的mycost值（假设代表某个成本中心，而不是价格;稍微难以分辨什么），你可以使用它而不是子查询
另请注意，如果您想添加过滤条件，例如要将数据限制到特定年份，您需要在left join子句中执行此操作，而不是作为where子句，或者将外部联接还原为内部联接。例如，adding this：
where mv.year = 2011
意味着你只能回到两行：
MONTH MYCOST MYNUMBER
----- ------ ----------
12 AAA 4337.75
12 BBB 5490.58
但是如果你made than another condition on the outer join，你仍然可以获得48行，其中46行有零，两行有上述值：
...
left join myoracle_mv mv
on mv.month = months.month
and mv.mycost = costs.mycost
and mv.year = 2011
order by months.month, costs.mycost, mv.mynumber;
...
11 CCC 0
11 DDD 0
12 AAA 4337.75
12 BBB 5490.58
12 CCC 0
12 DDD 0
48 rows selected
答案 1 :(得分：2)
您需要在两个内联视图之间进行外部联接
select MonthName, myCost, myNumber
from (select MONTH mm, myCost, myNumber
from myOracle_mv
) myTotals
right outer join
(select to_char(date '2012-12-1' + numtoyminterval(level,'month'), 'mm') MonthName
from dual
connect by level <= 12) ALLMONTHS
on( myTotals.mm = allmonths.MonthName )
您也可以使用旧的Oracle特定（+）语法进行外连接，但我通常建议使用SQL标准语法。
答案 2 :(得分：2)
也许是这样的
select MonthName, COALESCE(myCost,0), myNumber
from
(
select to_char(date '2012-12-1' + numtoyminterval(level,'month'), 'mm') MonthName
from dual
connect by level <= 12
) ALLMONTHS LEFT OUTER JOIN
(
select MONTH mm, myCost, myNumber
from myOracle_mv
) myTotals ON
mm = MonthName
答案 3 :(得分：1)
您需要在查询结尾处进行外部联接（(+)）：
select MonthName, myCost, myNumber from
(
select
MONTH mm, myCost, myNumber
from
myOracle_mv
) myTotals,
(
select
to_char(date '2012-12-1' + numtoyminterval(level,'month'), 'mm') MonthName
from
dual
connect by level <= 12
)ALLMONTHS
where mm = MonthName(+)
对于您的示例，您不需要计算日期：
select MONTH mm, NVL(myCost, 0), myNumber
from
(select level from dual connect by level <= 12) NUM
left outer join myOracle_mv MV ON ( MV.MONTH = NUM.level )
;