我有一个表 T1,它包含一个 NAME 值(不唯一)和一个日期范围(D1 和 D2 是日期) 当 NAME 相同时,我们对日期范围进行并集(例如 B)。
但是结果(X),我们需要对所有日期范围进行交集
编辑: 表 T1
NAME | D1 | D2
A | 20100101 | 20101211
B | 20100120 | 20100415
B | 20100510 | 20101230
C | 20100313 | 20100610
结果:
X | 20100313 | 20100415
X | 20100510 | 20100610
从视觉上看,这将给出以下内容:
NAME : date range
A : [-----------------------]-----
B : --[----]----------------------
B : ----------[---------------]---
C : -----[--------]---------------
结果:
X : -----[-]----------------------
X : ----------[---]---------------
知道如何使用 SQL / PL SQL 获得它吗?
这是一个快速解决方案(可能不是最有效的):
SQL> CREATE TABLE myData AS
2 SELECT 'A' name, date'2010-01-01' d1, date'2010-12-11' d2 FROM DUAL
3 UNION ALL SELECT 'B', date'2010-01-20', date'2010-04-15' FROM DUAL
4 UNION ALL SELECT 'B', date'2010-05-10', date'2010-12-30' FROM DUAL
5 UNION ALL SELECT 'C', date'2010-03-13', date'2010-06-10' FROM DUAL;
Table created
SQL> WITH segments AS (
2 SELECT dat seg_low, lead(dat) over(ORDER BY dat) seg_high
3 FROM (SELECT d1 dat FROM myData
4 UNION
5 SELECT d2 dat FROM myData)
6 )
7 SELECT s.seg_low, s.seg_high
8 FROM segments s
9 JOIN myData m ON s.seg_high > m.d1
10 AND s.seg_low < m.d2
11 GROUP BY s.seg_low, s.seg_high
12 HAVING COUNT(DISTINCT NAME) = 3;
SEG_LOW SEG_HIGH
----------- -----------
13/03/2010 15/04/2010
10/05/2010 10/06/2010
我构建所有可能的连续日期范围,并将此“日历”与示例数据连接起来。这将列出具有 3 个值的所有范围。如果添加行,您可能需要合并结果:
SQL> insert into mydata values ('B',date'2010-04-15',date'2010-04-16');
1 row inserted
SQL> WITH segments AS (
2 SELECT dat seg_low, lead(dat) over(ORDER BY dat) seg_high
3 FROM (SELECT d1 dat FROM myData
4 UNION
5 SELECT d2 dat FROM myData)
6 )
7 SELECT MIN(seg_low), MAX(seg_high)
8 FROM (SELECT seg_low, seg_high, SUM(gap) over(ORDER BY seg_low) grp
9 FROM (SELECT s.seg_low, s.seg_high,
10 CASE
11 WHEN s.seg_low
12 = lag(s.seg_high) over(ORDER BY s.seg_low)
13 THEN 0
14 ELSE 1
15 END gap
16 FROM segments s
17 JOIN myData m ON s.seg_high > m.d1
18 AND s.seg_low < m.d2
19 GROUP BY s.seg_low, s.seg_high
20 HAVING COUNT(DISTINCT NAME) = 3))
21 GROUP BY grp;
MIN(SEG_LOW) MAX(SEG_HIGH)
------------ -------------
13/03/2010 16/04/2010
10/05/2010 10/06/2010
我应该如何更改选择以处理同一天开始和结束的间隔的交集?