MySQL中JSON对象的部分更新

Question

下午好，

当我尝试使用 ON 更新 JSON 对象的一部分时DUPLICATE KEY UPDATE，如何使用键更新特定值？

代码执行成功，但当我只想库存在更新时发生变化时，所有值都会更新。

欢迎任何帮助，我不相信，我理解 MySQL JSON Path 语法，或者 JSON_SET 无法实现我的目标？

INSERT INTO table (name, attributes) VALUES
("Sarah", JSON_OBJECT('profile', "F", "el", "[4, 5, 6]")),
("John",  JSON_OBJECT('profile', "M", "el", "[10]"))
AS t
ON DUPLICATE KEY UPDATE
  attributes = JSON_SET(t.attributes, '$.attributes.el',  '$.attributes.el')
                                                         # ^
                                                         # +--- value being inserted

我还尝试过另一种口味，但没有成功：

attributes = JSON_REPLACE(t.attributes, '$.t.el', "$.t.el")

第三次尝试使用通配符和 json 提取，替换整个 JSON_OBJECT()

attributes = JSON_REPLACE(t.attributes, '$.t[2]', JSON_EXTRACT(t.attributes, "$.stock"))

Answer 1

如果我理解正确，您只需要使用语句内的 VALUES函数INSERT ... ON DUPLICATE KEY UPDATE即可访问要插入的值：

CREATE TABLE t(
  name varchar(100) NOT NULL UNIQUE,
  attributes JSON
);

INSERT INTO t(name, attributes) VALUES
('Sarah', '{"profile": "F", "el": ["insrted", 1]}'),
('John',  '{"profile": "M", "el": ["insrted", 2]}');

-- insert + on duplicate (mysql 5.x)
INSERT INTO t(name, attributes) VALUES
('Sarah', '{"profile": "F", "el": ["dup_upd", 3]}'),
('John',  '{"profile": "M", "el": ["dup_upd", 4]}'),
('Jack',  '{"profile": "M", "el": ["insrted", 1]}')
ON DUPLICATE KEY UPDATE attributes =
    JSON_SET(attributes, '$.el', JSON_EXTRACT(VALUES(attributes), '$.el'));

-- insert + on duplicate (mysql 8.x)
INSERT INTO t(name, attributes) VALUES
('Sarah', '{"profile": "F", "el": ["dup_upd", 3]}'),
('John',  '{"profile": "M", "el": ["dup_upd", 4]}'),
('Jack',  '{"profile": "M", "el": ["insrted", 1]}')
AS t_ins
ON DUPLICATE KEY UPDATE attributes =
    JSON_SET(t.attributes, '$.el', JSON_EXTRACT(t_ins.attributes, '$.el'));

SELECT name, JSON_PRETTY(attributes)
FROM t

CREATE TABLE t(
  name varchar(100) NOT NULL UNIQUE,
  attributes JSON
);

INSERT INTO t(name, attributes) VALUES
('Sarah', '{"profile": "F", "el": ["insrted", 1]}'),
('John',  '{"profile": "M", "el": ["insrted", 2]}');

-- insert + on duplicate (mysql 5.x)
INSERT INTO t(name, attributes) VALUES
('Sarah', '{"profile": "F", "el": ["dup_upd", 3]}'),
('John',  '{"profile": "M", "el": ["dup_upd", 4]}'),
('Jack',  '{"profile": "M", "el": ["insrted", 1]}')
ON DUPLICATE KEY UPDATE attributes =
    JSON_SET(attributes, '$.el', JSON_EXTRACT(VALUES(attributes), '$.el'));

-- insert + on duplicate (mysql 8.x)
INSERT INTO t(name, attributes) VALUES
('Sarah', '{"profile": "F", "el": ["dup_upd", 3]}'),
('John',  '{"profile": "M", "el": ["dup_upd", 4]}'),
('Jack',  '{"profile": "M", "el": ["insrted", 1]}')
AS t_ins
ON DUPLICATE KEY UPDATE attributes =
    JSON_SET(t.attributes, '$.el', JSON_EXTRACT(t_ins.attributes, '$.el'));

SELECT name, JSON_PRETTY(attributes)
FROM t

DB<>Fiddle 上的演示