PostgreSQL的jsonb_object_agg函数的两种用法

l1t2026-01-05 14:52

1.直接聚合成json格式

sql 复制代码

CREATE TABLE products (
    id SERIAL PRIMARY KEY,
    category TEXT,
    name TEXT,
    price NUMERIC
);
CREATE TABLE
Time: 7.595 ms
INSERT INTO products (category, name, price) VALUES
('Electronics', 'Laptop', 1200.00),
('Electronics', 'Smartphone', 800.00),
('Apparel', 'T-Shirt', 25.00),
('Apparel', 'Jeans', 75.00),
('Electronics', 'Headphones', 150.00);
INSERT 0 5
Time: 2.154 ms
SELECT
    category,
    jsonb_object_agg(name, price) AS products_detail
FROM products
GROUP BY category;
  category   |                         products_detail                         
-------------+-----------------------------------------------------------------
 Electronics | {"Laptop": 1200.00, "Headphones": 150.00, "Smartphone": 800.00}
 Apparel     | {"Jeans": 75.00, "T-Shirt": 25.00}
(2 rows)

Time: 0.378 ms

2.将每行记录构造成一个 jsonb 对象，然后用 jsonb_agg 聚合为数组

sql 复制代码

SELECT
    category,
    
    jsonb_agg(jsonb_build_object('name', name, 'price', price)) AS products_array
FROM products
GROUP BY category;
  category   |                                                      products_array                                                      
-------------+--------------------------------------------------------------------------------------------------------------------------
 Electronics | [{"name": "Laptop", "price": 1200.00}, {"name": "Smartphone", "price": 800.00}, {"name": "Headphones", "price": 150.00}]
 Apparel     | [{"name": "T-Shirt", "price": 25.00}, {"name": "Jeans", "price": 75.00}]
(2 rows)

Time: 0.438 ms