GROUP BY 组合连接列[重复]

GROUP BY 组合/连接列[重复]

sql
CREATE TABLE orders (
  order_id INT,
  customer_name VARCHAR(50),
  order_amount DECIMAL(10, 2)
);
INSERT INTO orders (order_id, customer_name, order_amount)
VALUES (1, 'John', 100.00),
       (2, 'John', 200.00),
       (3, 'Mary', 150.00),
       (4, 'Mary', 250.00),
       (5, 'Mary', 300.00);

sql
SELECT customer_name, SUM(order_amount) AS total_amount
FROM orders
GROUP BY customer_name, order_amount;

customer_name | total_amount
--------------|-------------
John          | 100.00
John          | 200.00
Mary          | 150.00
Mary          | 250.00
Mary          | 300.00