如何在Postgresql中选择和更新JSON数组元素？

发布时间：2020-12-13 16:04:34 所属栏目：百科来源：网络整理

导读：我正在使用9.6版本.我的文档看起来像这样： { "name" : "John Doe","phones" : [ { "type" : "mobile","number" : "555-555-0000","deleted": false },{ "type" : "home","number" : "555-555-0001","needsUpdated" : true },{ "type" : "work","number" : "

我正在使用9.6版本.我的文档看起来像这样：

{
    "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"
        }
    ]
}

我创建了这样的：

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","number":"555-555-0030"},"number":"555-555-0020"},"number": "555-555-0010"}]}');

现在我想弄清楚如何A,选择名为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我发现我可以查询这样的正确文件：

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

但我没有看到如何按类型选择手机阵列中的正确子文档,并更新数值.谁能帮我吗？

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.我非常确定此时无法在没有数据丢失的情况下进行此更新.

解决方法

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

如果您想获取电话号码,请使用此号码.相应文件是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);

如果您想通过电话号码搜索,这可以：

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

How to update the number value?

正如评论中所提到的,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','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';

（编辑：李大同）

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