Oracle关联查询问题?
查询结果如下列表:
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c1705_datetime c0003_stcode c0007_pcode c0001_item_code avg
1 2013-05-19 00:00 2 2013-05-19 01:00
3 2013-05-19 02:00
4 2013-05-19 03:00
5 2013-05-19 04:00
6 2013-05-19 05:00
7 2013-05-19 06:00
8 2013-05-19 07:00
9 2013-05-19 08:00
10 2013-05-19 09:00
11 2013-05-19 10:00 370102 218 101
12 2013-05-19 11:00 370102 218 101 0.091
13 2013-05-19 12:00 370102 218 101 0.017
14 2013-05-19 13:00 370102 218 101 0.036
15 2013-05-19 14:00 370102 218 101 0.047
16 2013-05-19 15:00 370102 218 101 0.044
17 2013-05-19 16:00 370102 218 101 0.047
18 2013-05-19 17:00 370102 218 101 0.045
19 2013-05-19 18:00 370102 218 101 0.045
20 2013-05-19 19:00 370102 218 101 0.069
21 2013-05-19 20:00 370102 218 101 0.051
22 2013-05-19 21:00 370102 218 101 0.049
23 2013-05-19 22:00 370102 218 101 0.082
24 2013-05-19 23:00 370102 218 101 0.082
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我实现的是和时间表关联,如果没数据也显示时间列。但是我想没数据时,c0003_stcode c0007_pcode c0001_item_code也显示出来,avg显示为空,就象如下样式:
c1705_datetime c0003_stcode c0007_pcode c0001_item_code avg
11 2013-05-19 10:00 370102 218 101
请问关联SQL语句怎么写?