Question

我的PostgreSQL 9.6实例中有两个表。

users

+----+------------+-----------+-------------------+
| id | first_name | last_name | email             |
+----+------------+-----------+-------------------+
| 1  | John       | Doe       | john.doe@test.com |
+----+------------+-----------+-------------------+
| 2  | Jane       | Doe       | jane.doe@test.com |
+----+------------+-----------+-------------------+
| 3  | Mike       | Doe       | mike.doe@test.com |
+----+------------+-----------+-------------------+


surveys
+----+---------+----------------------------------------------------------------------------------------------------+
| id | user_id | survey_data                                                                                        |
+----+---------+----------------------------------------------------------------------------------------------------+
| 1  | 1       | {'child_list': [{'gender': 1, 'birthday': '2015-10-01'}, {'gender': 2, 'birthday': '2017-05-01'}]} |
+----+---------+----------------------------------------------------------------------------------------------------+
| 2  | 2       | {'child_list': []}                                                                                 |
+----+---------+----------------------------------------------------------------------------------------------------+
| 3  | 3       | {'child_list': [{'gender': 2, 'birthday': '2008-01-01'}]}                                          |
+----+---------+----------------------------------------------------------------------------------------------------+

我希望能够查询这两个表，以获取在一定年龄之间有孩子的用户数量。 survey_data表中的surveys列是JSONB列。

到目前为止，我已经尝试将jsonb_populate_recordset与LATERAL连接一起使用。我能够将SELECT child_list数组分为两列，但无法弄清楚如何在JOIN和users表之间的surveys中使用该数组。我使用的查询如下：

SELECT DISTINCT u.email
FROM surveys
  CROSS  JOIN LATERAL (
   SELECT *
   FROM  jsonb_populate_recordset(null::json_type, (survey.survey_data->>'child_list')::jsonb) AS d
   ) d
INNER JOIN users u ON u.id = survey.user_id
WHERE d.birthday BETWEEN '2014-05-05' AND '2018-05-05';

这也使用使用以下方法创建的自定义类型：

CREATE type json_type AS (gender int, birthday date)

我的问题是，有一种更容易阅读的方式来做到这一点吗？我想将此查询与其他许多JOIN和WHERE子句一起使用，我想知道是否有更好的方法可以做到这一点。

注意：这主要将用于报告系统，该系统不需要超快，但是当然可以提高速度。

Answer 1

使用函数jsonb_array_elements(),示例：

select email, (elem->>'gender')::int as gender, (elem->>'birthday')::date as birthday
from users u
left join surveys s on s.user_id = u.id
cross join jsonb_array_elements(survey_data->'child_list') as arr(elem)

       email       | gender |  birthday  
-------------------+--------+------------
 john.doe@test.com |      1 | 2015-10-01
 john.doe@test.com |      2 | 2017-05-01
 mike.doe@test.com |      2 | 2008-01-01
(3 rows)

或

select distinct email
from users u
left join surveys s on s.user_id = u.id
cross join jsonb_array_elements(survey_data->'child_list') as arr(elem)
where (elem->>'birthday')::date between '2014-05-05' and '2018-05-05';

       email       
-------------------
 john.doe@test.com
(1 row)

使用视图可以使生活更轻松：

create view users_children as
    select email, (elem->>'gender')::int as gender, (elem->>'birthday')::date as birthday
    from users u
    left join surveys s on s.user_id = u.id
    cross join jsonb_array_elements(survey_data->'child_list') as arr(elem);

select distinct email
from users_children
where birthday between '2014-05-05' and '2018-05-05';

按日期搜索PostgreSQL JSONB列中的对象数组

1 个答案: