sql - 如何在 Postgresql 中选择和更新 JSON 数组元素？

Question

我使用的是 9.6 版。我有这样的文档:

{
    "name" : "John Doe", 
    "phones" : [
        {
            "type" : "mobile", 
            "number" : "555-555-0000",
            "deleted": false
        }, 
        {
            "type" : "home", 
            "number" : "555-555-0001",
            "needsUpdated" : true
        }, 
        {
            "type" : "work", 
            "number" : "555-555-0002"
        }
    ]
}

我是这样创建的:

create table t_json (c_json json not null);

insert into t_json (c_json) values ('{"name":"John Doe","phones": [{"type":"mobile","number":"555-555-0000"},{"type":"home","number":"555-555-0001"},{"type": "work","number": "555-555-0002"}]}');

insert into t_json (c_json) values ('{"name":"Jane Dane","phones": [{"type":"mobile","number":"555-555-0030"},{"type":"home","number":"555-555-0020"},{"type": "work","number": "555-555-0010"}]}');

现在我想弄清楚如何A，选择名称为 John Doe 的行，并将他的手机号码更新为“555-555-0003 ".

从这里Postgresql 9.6 documentation我发现我可以像这样查询正确的文档:

select c_json from t_json where c_json->>'name' = 'John Doe';

但我没有看到如何按类型在电话数组中选择正确的子文档，并更新数字值。谁能帮帮我？

编辑

我需要假设子文档有额外的值并且不一致。所以我在上面添加了一些。我很确定此时如果不丢失数据就不可能进行此更新。

Answer 1

How to select the proper sub-document in the phones array by type?

如果你想得到电话号码，使用这个。对应文件为https://www.postgresql.org/docs/9.6/static/queries-table-expressions.html#QUERIES-LATERAL

SELECT c_json ->> 'name', phones.type, phones.number
    FROM t_json
    CROSS JOIN json_to_recordset(c_json -> 'phones')
        AS phones("type" TEXT, "number" TEXT);

如果你想按电话号码搜索，这行得通:

SELECT * FROM t_json
    WHERE (c_json -> 'phones')::JSONB @>
        '[{"type":"mobile","number":"555-555-0000"}]'::JSONB;

How to update the number value?

如评论中所述，有一个类似的问题，How do I modify fields inside the new PostgreSQL JSON datatype?

还有其他方法可以做到这一点，比如

UPDATE t_json SET c_json = newvalue FROM (
    SELECT to_json(updated) AS newvalue FROM (
        SELECT c_json ->> 'name' as "name",
            json_agg(json_build_object('type', phones.type, 'number',
                CASE phones.type WHEN 'mobile' THEN '555-555-0003' ELSE phones.number END)
            ) AS phones
    FROM t_json
    CROSS JOIN json_to_recordset(c_json -> 'phones')
        AS phones("type" TEXT, "number" TEXT)
    WHERE c_json->>'name' = 'John Doe'
    GROUP BY name
    ) as updated
) AS sub WHERE c_json ->> 'name' = 'John Doe';