mysql 插入数据必须更新

DELIMITER //
CREATE TRIGGER update_inventory_after_insert
AFTER INSERT ON orders
FOR EACH ROW
BEGIN
    UPDATE inventory
    SET quantity = quantity - NEW.quantity
    WHERE product_id = NEW.product_id;
END //
DELIMITER ;

DELIMITER //
CREATE PROCEDURE insert_order_with_inventory_update(
    IN p_product_id INT,
    IN p_quantity INT
)
BEGIN
    INSERT INTO orders (product_id, quantity) VALUES (p_product_id, p_quantity);
    UPDATE inventory SET quantity = quantity - p_quantity WHERE product_id = p_product_id;
END //
DELIMITER ;

# 示例代码（Python）
import mysql.connector

def insert_order_and_update_inventory(product_id, quantity):
    conn = mysql.connector.connect(user='user', password='password', host='host', database='database')
    cursor = conn.cursor()
    
    try:
        # 插入订单
        insert_query = "INSERT INTO orders (product_id, quantity) VALUES (%s, %s)"
        cursor.execute(insert_query, (product_id, quantity))
        
        # 更新库存
        update_query = "UPDATE inventory SET quantity = quantity - %s WHERE product_id = %s"
        cursor.execute(update_query, (quantity, product_id))
        
        conn.commit()
    except mysql.connector.Error as err:
        print(f"Error: {err}")
        conn.rollback()
    finally:
        cursor.close()
        conn.close()

# 调用函数
insert_order_and_update_inventory(1, 10)