对象和数组类型

# 将联合查询到的数据转成对象（一对多）
SELECT
products.id id, products.title title, products.price price,
JSON_OBJECT('id', brand.id, 'name', brand.name, 'website', brand.website) brand
FROM `products`
LEFT JOIN `brand` ON products.brand_id = brand.id;

# 将查询到的多条数据，组织成对象，放入到一个数组中(多对多)
SELECT
stu.id, stu.name, stu.age,
JSON_ARRAYAGG(JSON_OBJECT('id', cs.id, 'name', cs.name, 'price', cs.price))
FROM `students` stu
JOIN `students_select_courses` ssc ON stu.id = ssc.student_id
JOIN `courses` cs ON ssc.course_id = cs.id
GROUP BY stu.id;

SELECT * FROM products WHERE price > 6000;