在postgres中将jsonb转换为常规数组

Question

我有以下 table：

"Id"|                  "Data"
====+================================================
1   | { "emp": [ 
    |            {"id": "a1", "otherdata": "other"}, 
    |            {"id": "a2", "otherdata": "other"} 
    |          ]
    | }
----+------------------------------------------------
2   | { "emp": [ 
    |            {"id": "b1", "otherdata": "other"}, 
    |            {"id": "b2", "otherdata": "other"} 
    |          ]
    | }
-----------------------------------------------------

其中 "Data" 是 jsonb。

我需要创建一个临时 table 这种类型：

"Id"| "Emp"
====+=============
1   | {"a1", "a2"}
----+-------------
2   | {"b1", "b2"}

我该怎么做？

Answer 1

使用 jsonb_to_recordset 将数组值提取到行中，将它们分组，然后使用 array_to_json.

返回数组

SELECT a.id, array_to_json(array_agg(b.id)) AS emp
FROM mytable a
CROSS JOIN jsonb_to_recordset(a.data->'emp') AS b(id text)
GROUP BY a.id;

见SQL Fiddle

在postgres中将jsonb转换为常规数组

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