如何解决如何有效查询数据集中的连续日期集？
这是有关如何执行此查询的示例：
sql> create table t (site_id,start_date,end_date)
2 as
3 select 1, date '2008-10-01', date '2008-10-02' from dual union all
4 select 1, date '2008-10-02', date '2008-10-03' from dual union all
5 select 1, date '2008-10-03', date '2008-10-30' from dual union all
6 select 1, date '2008-10-30', date '2008-10-31' from dual union all
7 select 2, date '2008-10-01', date '2008-10-02' from dual union all
8 select 2, date '2008-10-02', date '2008-10-03' from dual union all
9 select 2, date '2008-10-03', date '2008-10-04' from dual union all
10 select 2, date '2008-10-04', date '2008-10-05' from dual union all
11 select 2, date '2008-10-05', date '2008-10-06' from dual union all
12 select 2, date '2008-10-06', date '2008-10-07' from dual union all
13 select 2, date '2008-10-07', date '2008-10-08' from dual union all
14 select 2, date '2008-10-08', date '2008-10-09' from dual union all
15 select 2, date '2008-10-09', date '2008-10-10' from dual union all
16 select 2, date '2008-10-10', date '2008-10-11' from dual union all
17 select 2, date '2008-10-11', date '2008-10-12' from dual union all
18 select 2, date '2008-10-12', date '2008-10-13' from dual union all
19 select 2, date '2008-10-13', date '2008-10-14' from dual union all
20 select 2, date '2008-10-14', date '2008-10-15' from dual union all
21 select 2, date '2008-10-15', date '2008-10-16' from dual union all
22 select 2, date '2008-10-16', date '2008-10-17' from dual union all
23 select 2, date '2008-10-17', date '2008-10-18' from dual union all
24 select 2, date '2008-10-18', date '2008-10-19' from dual union all
25 select 2, date '2008-10-19', date '2008-10-20' from dual union all
26 select 3, date '2008-10-01', date '2008-10-02' from dual union all
27 select 3, date '2008-10-02', date '2008-10-03' from dual union all
28 select 3, date '2008-10-03', date '2008-10-04' from dual union all
29 select 3, date '2008-10-04', date '2008-10-05' from dual union all
30 select 3, date '2008-10-05', date '2008-10-06' from dual union all
31 select 3, date '2008-10-06', date '2008-10-07' from dual union all
32 select 3, date '2008-10-07', date '2008-10-08' from dual union all
33 select 3, date '2008-10-08', date '2008-10-09' from dual union all
34 select 3, date '2008-10-09', date '2008-10-10' from dual union all
35 select 3, date '2008-10-30', date '2008-10-31' from dual
36 /
Tabel is aangemaakt.
然后查询：
sql> select site_id
2 , min(start_date) contiguous_start_date
3 , max(end_date) contiguous_end_date
4 , count(*) number_of_contiguous_records
5 from ( select site_id
6 , start_date
7 , end_date
8 , max(rn) over (partition by site_id order by start_date) maxrn
9 from ( select site_id
10 , start_date
11 , end_date
12 , case lag(end_date) over (partition by site_id order by start_date)
13 when start_date then null
14 else rownum
15 end rn
16 from t
17 )
18 )
19 group by site_id
20 , maxrn
21 order by site_id
22 , contiguous_start_date
23 /
结果：
SITE_ID CONTIGUOUS_START_DA CONTIGUOUS_END_DATE NUMBER_OF_CONTIGUOUS_RECORDS
---------- ------------------- ------------------- ----------------------------
1 01-10-2008 00:00:00 31-10-2008 00:00:00 4
2 01-10-2008 00:00:00 20-10-2008 00:00:00 19
3 01-10-2008 00:00:00 10-10-2008 00:00:00 9
3 30-10-2008 00:00:00 31-10-2008 00:00:00 1
4 rijen zijn geselecteerd.
问候，罗布。
解决方法
site_id | start_date | end_date
1 | oct 1,08 | oct 2,08
1 | oct 2,08 | oct 3,08
...
1 | oct 30,08 | oct 31,08
2 | oct 1,08
2 | oct 2,08
...
2 | oct 30,08
我有一个表，每个月的每月（一年中的每个月）包含1条记录。我需要确定给定月份的站点是否至少有15个连续记录，并且我需要知道该连续天数的开始和结束日期。我可以在存储过程中执行此操作，但我希望可以在单个查询中完成此操作。我正在处理一个相当大的数据集，每月至少有3000万条记录。
结果示例：
site_id | contiguous_start_date | contiguous_end_date
1 | oct 5,2008 | oct 20,2008
2 | oct 10 | oct 30,2008
3 | oct 1 | oct 31,2008
感谢您的帮助！
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