按特定时间段拆分（如：按最近 2-3 个月...4-5 个月、6-7 个月拆分数据）

Question

我有一个简单的问题，我不知道我哪里做错了。非常感谢你的帮助。预先感谢您的任何提示。

我有数据，需要将发布日期拆分为 1 个月、2-3 个月、4-5 个月、6-7 个月、7-9 个月等。所以，我创建了一个查询；

Select    case
          when release_date >= current_date - interval '1 month' then 'Within 1 month'
          when release_date between (current_date - interval '2 months') and (current_date - interval '3 months') then '2-3 months'
          when release_date between (current_date - interval '4 months') and (current_date - interval '5 months') then '4-5 months'
          when release_date between (current_date - interval '6 months') and (current_date - interval '7 months') then '6-7 months'
          when release_date between (current_date - interval '8 months') and (current_date - interval '9 months') then '8-9 months'
          when release_date between (current_date - interval '10 months') and (current_date - interval '12 months') then '9-12 months'
          when release_date < current_date - interval '12 months' then '> 12 month'
          end as release_date,
          country,
          ....

最后我只能看到1个月内，NULL和>12个月.

Answer 1

如果我没看错您的查询，您需要交换“between”语句中的值：

Select    case
          when release_date >= current_date - interval '1 month' then 'Within 1 month'
          when release_date between (current_date - interval '3 months') and (current_date - interval '2 months') then '2-3 months'
          when release_date between (current_date - interval '5 months') and (current_date - interval '4 months') then '4-5 months'
          when release_date between (current_date - interval '7 months') and (current_date - interval '6 months') then '6-7 months'
          when release_date between (current_date - interval '9 months') and (current_date - interval '8 months') then '8-9 months'
          when release_date between (current_date - interval '12 months') and (current_date - interval '9 months') then '9-12 months'
          when release_date < current_date - interval '12 months' then '> 12 month'
          end as release_date,
          country,

我没有系统可以运行确认这一点，但它应该可以工作。

问题是 between 的工作方式，BETWEEN (lower_limit) AND (upper_limit)。

Answer 2

我认为您的输出生成的计算不是“月”。答案取决于您使用的是哪个数据库管理系统。这是在 postgres 中执行的一种方法，但如果您使用的是另一个 dbms，那么您应该能够轻松更改 CTE 中计算月份的语法。使用 CTE 可以让您有一个干净的 case 语句。

    with calculated_months as
    (
      select release_date,  
      extract(year from age(current_date, release_date)) * 12
       + extract(month from age(current_date, release_date))
       + 1   as months_from_current
    from t1
    )
    select t.release_date, 
    case
        when c.months_from_current < 2 then 'Within 1 month'
        when c.months_from_current between 2 and 3 then '2-3 months'
        when c.months_from_current between 4 and 5 then '4-5 months'
        when c.months_from_current between 6 and 7 then '6-7 months'
        when c.months_from_current between 8 and 9 then '8-9 months'
        when c.months_from_current between 10 and 12 then '10-12 months'
        when c.months_from_current > 12 then '12+ months'
    end months_since_release,
    t.country
    from t1 t
    join calculated_months c
      on c.release_date = t.release_date

db-fiddle here

编辑：不确定您的数据如何显示，但您可能想在 CTE 中添加一个“不同的”（select 不同的发布日期...）。

按特定时间段拆分（如：按最近 2-3 个月...4-5 个月、6-7 个月拆分数据）

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