Question

我有一个包含以下数据的表：

+------------+-------------+---------------+
| shop_id    |  visit_date | visit_reason  |
+------------+-------------+---------------+
|      A     | 2010-06-14  | shopping      |
|      A     | 2010-06-15  | browsing      |
|      B     | 2010-06-16  | shopping      |
|      B     | 2010-06-14  | stealing      |
+------------+-------------+---------------|

我需要建立一个汇总表，该表按商店，年，月，活动以及年和月的总值分组。例如，如果商店A每月有10次销售，每月有2次盗窃，并且没有其他类型的访问，那么回报将是：

shop_id, year, month, reason, reason_count, month_count, year_count

  A,     2010, 06,    shopping, 10,         12,          144
  A,     2010, 06,    stealing, 2,          12,          144

其中month_count是2010-06年该商店的任何类型的访问总次数。除2010年外，年数相同。

我可以使用以下方法获得除月份和年份之外的所有内容：

SELECT 
  shop_id, 
  extract(year from visit_date) as year,
  extract(month from visit_date) as month,
  visit_reason as reason,
  count(visit_reason) as reason_count,
FROM shop_visits
GROUP BY shop_id, year, month

我应该使用某种CTE分组吗？

Answer 1

您可以使用窗口功能来累加计数。以下是使用date_trunc()的短语，我发现按月进行汇总更方便：

select shop_id, date_trunc('month', visit_date) as yyyymm, reason,
       count(*) as month_count,
       sum(count(*)) over (partition by shop_id, date_trunc('year', min(visit_date))) as year_count
from t
group by shop_id, date_trunc('month', visit_date), reason;

在Postgres中汇总多个组

1 个答案: