Question

您好我想在Postgresql中使用generate_series制作动态时间序列。

例如，我有一组随机日期列表：

cleaning date
2015-03-01 00:00
2015-05-31 00:00
2015-06-13 00:00

我希望按照这些清洁日期动态分割日期。

结果如下：

start date         end date
0000-00-00 00:00   2015-03-01 00:00
2015-03-01 00:00   2015-05-31 00:00
2015-05-31 00:00   2015-06-13 00:00
2015-06-13 00:00   (current_timestamp)

我不知道如何在generate_series中设置动态区间... 这可能是generate_series吗？

Answer 1

我真的没有意识到使用generate_series。

要获得您建议的结果，您可以使用ROW_NUMBER并自行加入：

CREATE TABLE tab(cleaning timestamp);

INSERT INTO tab(cleaning)
VALUES ('2015-03-01 00:00'), ('2015-05-31 00:00'), ('2015-06-13 00:00');

主要查询：

WITH cte AS
(
   SELECT cleaning, ROW_NUMBER() OVER(ORDER BY cleaning) AS rn
   FROM tab
)
SELECT COALESCE(c1.cleaning,'0001-01-01'::timestamp) AS start_date,
       COALESCE(c2.cleaning,CURRENT_TIMESTAMP) AS end_date
FROM cte c1
FULL JOIN cte c2
  ON c1.rn = c2.rn-1
ORDER BY start_date;

的 SqlFiddleDemo

输出：

╔═══════════════════════════╦═════════════════════════╗ ║ start_date ║ end_date ║ ╠═══════════════════════════╬═════════════════════════╣ ║ January, 01 0001 00:00:00 ║ March, 01 2015 00:00:00 ║ ║ March, 01 2015 00:00:00 ║ May, 31 2015 00:00:00 ║ ║ May, 31 2015 00:00:00 ║ June, 13 2015 00:00:00 ║ ║ June, 13 2015 00:00:00 ║ March, 30 2016 11:03:38 ║ ╚═══════════════════════════╩═════════════════════════╝

修改

另一种可能性是使用LAG/LEAD窗口函数：

SELECT COALESCE(LAG(cleaning) OVER(ORDER BY cleaning), '0001-01-01'::timestamp) AS start_date ,cleaning AS end_date FROM tab UNION ALL SELECT MAX(cleaning), CURRENT_TIMESTAMP FROM tab ORDER BY start_date;

的 SqlFiddleDemo2

Postgresql generate_series动态区间

1 个答案: