问题描述
我有一个四列的表格。我想为从 id 到 date1 的每个 date3 创建一个具有 1 天间隔的日期列。如果没有date3，那么直到date2，如果没有date2，那么只有date1。
如何在 Postgres 中实现这一点？谢谢！
示例数据：
+-------+---------------------+---------------------+---------------------+
| id | date1 | date2 | date3 |
+-------+---------------------+---------------------+---------------------+
| 76efg | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 |
| b67cs | 2021-01-09 03:45:24 | 2021-01-14 06:55:13 | |
| fsf56 | 2021-01-25 11:18:03 | 2021-01-25 11:18:03 | |
| ghl56 | 2021-01-29 14:25:57 | 2021-02-02 17:37:10 | 2021-02-18 01:13:37 |
| 90tum | 2021-02-18 06:13:30 | | |
+-------+---------------------+---------------------+---------------------+
id '76efg' 的期望输出：
+-------+--------------+---------------------+---------------------+---------------------+--+
| id | date_created | date1 | date2 | date3 | |
+-------+--------------+---------------------+---------------------+---------------------+--+
| 76efg | 2021-01-03 | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 | |
| 76efg | 2021-01-04 | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 | |
| 76efg | 2021-01-05 | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 | |
| 76efg | 2021-01-06 | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 | |
| 76efg | 2021-01-07 | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 | |
| 76efg | 2021-01-08 | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03 | |
+-------+--------------+---------------------+---------------------+---------------------+--+
解决方法
您是否尝试过使用 generated_series()？以下查询基于 date1、date2 和 date3 以及使用 COALESCE 找到的系列的限制生成一系列时间戳 - 基本上检查列是否为 {{ 1}} .
null检查这个db<>fiddle。
感谢@clamp 关于 WITH j (id,date1,date2,date3) AS (
VALUES ('76efg','2021-01-03 06:33:54'::TIMESTAMP,'2021-01-07 05:19:03'::TIMESTAMP,'2021-01-08 05:19:03'::TIMESTAMP ),('b67cs','2021-01-09 03:45:24'::TIMESTAMP,'2021-01-14 06:55:13'::TIMESTAMP,NULL),('90tum','2021-02-18 06:13:30'::TIMESTAMP,NULL,NULL)
)
SELECT
id,generate_series(
date1,COALESCE(date3,date1),'1 day'::INTERVAL) AS date_created,date3
FROM j;
id | date_created | date2 | date3
-------+---------------------+---------------------+---------------------
76efg | 2021-01-03 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03
76efg | 2021-01-04 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03
76efg | 2021-01-05 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03
76efg | 2021-01-06 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03
76efg | 2021-01-07 06:33:54 | 2021-01-07 05:19:03 | 2021-01-08 05:19:03
b67cs | 2021-01-09 03:45:24 | 2021-01-14 06:55:13 |
b67cs | 2021-01-10 03:45:24 | 2021-01-14 06:55:13 |
b67cs | 2021-01-11 03:45:24 | 2021-01-14 06:55:13 |
b67cs | 2021-01-12 03:45:24 | 2021-01-14 06:55:13 |
b67cs | 2021-01-13 03:45:24 | 2021-01-14 06:55:13 |
b67cs | 2021-01-14 03:45:24 | 2021-01-14 06:55:13 |
90tum | 2021-02-18 06:13:30 | |
的提示：
COALESCE(COALESCE(date3,date2),date1) 等价于 COALESCE(date3,date1)