使用带有聚合计数的连接的 SQL 选择查询

Question

我有一个包含以下字段的表：

tickets:  id, createddate, resolutiondate

一组样本数据具有：

jira=# select * from tickets;
   id    | createddate | resolutiondate
---------+-------------+----------------
 ticket1 | 2020-09-21  | 2020-10-01
 ticket2 | 2020-09-22  | 2020-09-23
 ticket3 | 2020-10-01  |
 ticket4 | 2020-10-01  | 2020-10-04
 ticket5 | 2020-10-01  |
 ticket6 | 2020-10-01  | 2020-10-07
(6 rows)

jira=#

我想创建一个报告的查询：

Week:  Issues Created:  Issues Resolved

我可以做两个单独的查询：

# select date_trunc('week', createddate) week, count(id) created
    from tickets
    group by week
    order by week desc
    ;
          week          | created
------------------------+---------
 2020-09-28 00:00:00+00 |       4
 2020-09-21 00:00:00+00 |       2
(2 rows)

# select date_trunc('week', resolutiondate) week, count(id) resolved
    from tickets
    where resolutiondate is not NULL
    group by week
    order by week desc
    ;

          week          | resolved
------------------------+----------
 2020-10-05 00:00:00+00 |        1
 2020-09-28 00:00:00+00 |        2
 2020-09-21 00:00:00+00 |        1
(3 rows)

但是 - 我无法弄清楚如何（使用连接、联合、子查询，...？）将这些查询组合成具有适当聚合的组合查询。

我正在做的是 Postgres - 任何指针将不胜感激。

Answer 1

在聚合值之前执行联合可能在这里工作，例如

select week, 
       count(id_created) as created,
       count(id_resolved) as resolved
from (
    select date_trunc('week', resolutiondate) week, NULL as id_created, id as id_resolved from tickets UNION ALL
    select date_trunc('week', createddate) week, id as id_created, NULL as id_resolved from tickets
) t
    group by week
    order by week desc

让我知道这是否适合您。