生成开始日期和结束日期内的所有季度答案

【问题标题】：Generate all quarters within a start date and end date生成开始日期和结束日期内的所有季度
【发布时间】：2017-06-09 00:22:00
【问题描述】：

我有一张包含不同广告系列的表格。每个广告系列都有一个开始日期和结束日期。

campaign id | start date | end date |

我想知道这些活动发生在哪个季度。

理想情况下，它应该是这样的——在那些四分之一列下，它会显示一个 0 和 1 的二进制变量。

account id | campaign id | start date | end date | 2015q1 | 2015q2 | 2015q3 |...etc

例如，如果活动在 2015 年 1 月 1 日至 2015 年 5 月 2 日期间发生，那么结果将是：

| 2015q1 | 2015q2 | 2015q3 |
| 1      | 1      | 0      |

我正在使用 Amazon Redshift。

【问题讨论】：

标签： sql amazon-redshift

【解决方案1】：

将结果放入列时，您必须对值进行硬编码。比如这个输入数据：

id, start_date,end_date
1,2016-03-23,2016-07-18
2,2016-01-01,2016-01-02
3,2016-10-05,2016-11-05
4,2016-01-01,2016-12-31

使用此查询：

SELECT
  id,
  start_date,
  end_date,
  (CASE WHEN start_date < '2016-04-01' AND end_date >= '2016-01-01' THEN 1 ELSE 0 END) as Q1_2016,
  (CASE WHEN start_date < '2016-07-01' AND end_date >= '2016-04-01' THEN 1 ELSE 0 END) as Q2_2016,
  (CASE WHEN start_date < '2016-10-01' AND end_date >= '2016-07-01' THEN 1 ELSE 0 END) as Q3_2016,
  (CASE WHEN start_date < '2017-01-01' AND end_date >= '2016-10-01' THEN 1 ELSE 0 END) as Q4_2016
FROM campaign

给出这个结果：

1   2016-03-23  2016-07-18  1   1   1   0
2   2016-01-01  2016-01-02  1   0   0   0
3   2016-10-05  2016-11-05  0   0   0   1
4   2016-01-01  2016-12-31  1   1   1   1

很遗憾，没有可以为您自动创建列的 SQL 技巧。

【讨论】：

【解决方案2】：

你可以使用如下extract(Quarter from date)函数：

SELECT
   campaign_id,
   case when start_quarter=1 and start_year=2015 then 1 else 0 end as q1_2015,
   case when start_quarter=2 and start_year=2015 then 1 else 0 end as q2_2015,
   case when start_quarter=3 and start_year=2015 then 1 else 0 end as q3_2015,
   case when start_quarter=4 and start_year=2015 then 1 else 0 end as q4_2015
FROM (
  SELECT
    campaign_id,
    extract(MONTH FROM start_date) AS start_month,
    extract(YEAR FROM start_date)  AS start_year,
    extract(QUARTER from start_date) as start_quarter,
    extract(MONTH FROM end_date)   AS end_month,
    extract(YEAR FROM end_date)    AS end_year,
    extract(QUARTER FROM end_date) AS end_quarter
  FROM table
) t1

或者，如果您更喜欢没有硬编码的选项，您可以简单地使用子查询。

SELECT
    campaign_id,
    extract(MONTH FROM start_date) AS start_month,
    extract(YEAR FROM start_date)  AS start_year,
    extract(QUARTER from start_date) as start_quarter,
    extract(MONTH FROM end_date)   AS end_month,
    extract(YEAR FROM end_date)    AS end_year,
    extract(QUARTER FROM end_date) AS end_quarter
  FROM table

此选项将为您提供如下结果：

campaing_id start month start year  start quarter   end month   end year    end quarter
    4   2015    2   4   2015    2
    3   2017    1   3   2017    1
    2   2015    1   3   2015    1
    12  2014    4   12  2014    4
    2   2017    1   2   2017    1
    7   2016    3   8   2016    3

【讨论】：