MySQL の JSON

CREATE TABLE products (
    id         INT PRIMARY KEY AUTO_INCREMENT,
    name       VARCHAR(100) NOT NULL,
    attributes JSON
);

INSERT INTO products (name, attributes) VALUES (
    'Laptop',
    '{"brand": "Acme", "ram_gb": 16, "tags": ["portable", "pro"]}'
);

-- These are equivalent
SELECT JSON_EXTRACT(attributes, '$.brand') FROM products;
SELECT attributes -> '$.brand' FROM products;

SELECT attributes ->> '$.brand' FROM products;  -- returns: Acme

-- Find all 16GB RAM products
SELECT name FROM products
WHERE attributes ->> '$.ram_gb' = '16';

-- Check if a key exists
SELECT name FROM products
WHERE JSON_EXTRACT(attributes, '$.brand') IS NOT NULL;

-- Check if an array contains a value
SELECT name FROM products
WHERE JSON_CONTAINS(attributes -> '$.tags', '"portable"');

-- Add or update a field
UPDATE products
SET attributes = JSON_SET(attributes, '$.color', 'silver')
WHERE id = 1;

-- Remove a field
UPDATE products
SET attributes = JSON_REMOVE(attributes, '$.tags')
WHERE id = 1;

-- Insert only if the key doesn't exist
UPDATE products
SET attributes = JSON_INSERT(attributes, '$.warranty_years', 2)
WHERE id = 1;

ALTER TABLE products
    ADD COLUMN brand VARCHAR(100) GENERATED ALWAYS AS (attributes ->> '$.brand') VIRTUAL;

CREATE INDEX idx_brand ON products (brand);