Postgres:将JSON列扩展为行

Question

在Postgres 9.3数据库中,我有一个表,其中一列包含JSON,如下面示例中显示的测试表中所示.

test=# create table things (id serial PRIMARY KEY, details json, other_field text);
CREATE TABLE
test=# \d things
                            Table "public.things"
   Column    |  Type   |                      Modifiers
-------------+---------+-----------------------------------------------------
 id          | integer | not null default nextval('things_id_seq'::regclass)
 details     | json    |
 other_field | text    |
Indexes:
    "things_pkey" PRIMARY KEY, btree (id)

test=# insert into things (details, other_field) 
       values ('[{"json1": 123, "json2": 456},{"json1": 124, "json2": 457}]', 'nonsense');
INSERT 0 1
test=# insert into things (details, other_field) 
       values ('[{"json1": 234, "json2": 567}]', 'piffle');
INSERT 0 1
test=# select * from things;
 id |                           details                           | other_field
----+-------------------------------------------------------------+-------------
  1 | [{"json1": 123, "json2": 456},{"json1": 124, "json2": 457}] | nonsense
  2 | [{"json1": 234, "json2": 567}]                              | piffle
(2 rows)

JSON始终是包含可变数量哈希的数组.每个哈希都具有相同的密钥集.我正在尝试编写一个查询,该查询为JSON数组中的每个条目返回一行,每个哈希键的列和来自things表的id.我希望输出如下:

 thing_id | json1 | json2
----------+-------+-------
        1 |   123 |   456
        1 |   124 |   457
        2 |   234 |   567

即两行用于JSON数组中具有两个项的条目.是否有可能让Postgres这样做？ json_populate_recordset感觉就像答案的一个重要部分,但我不能让它同时与多行一起工作.

Answer 1

select id,
    (details ->> 'json1')::int as json1,
    (details ->> 'json2')::int as json2
from (
    select id, json_array_elements(details) as details
    from things
) s
;
 id | json1 | json2 
----+-------+-------
  1 |   123 |   456
  1 |   124 |   457
  2 |   234 |   567