按价格给商品分档，新增一列 band：
| 条件 | band |
|---|---|
price < 50 |
low |
50 ≤ price < 200 |
mid |
price ≥ 200 |
high |
mid，恰好 200 是 high。price 为 null 时 band 也为 null，不要归入任何一档（第二个 case 里有）。输入
products(product_id, name, category, price, cost, launched_on)输出
列为 product_id, price, band，每个商品一行，行顺序不限。
products shop/products
| # | product_idint64 | namestring | categorystring | pricefloat64 | costfloat64 | launched_ondate |
|---|---|---|---|---|---|---|
| 1 | 1 | Wireless Mouse | Electronics | 25.0 | 16.77 | 2025-05-07 |
| 2 | 2 | USB-C Hub | Electronics | 49.9 | 34.17 | 2025-07-27 |
| 3 | 3 | Bluetooth Speaker | Electronics | 89.0 | 61.47 | 2025-02-10 |
| 4 | 4 | Mechanical Keyboard | Electronics | 199.0 | 105.48 | 2024-09-19 |
| 5 | 5 | 4K Monitor | Electronics | 500.0 | 282.38 | 2024-07-10 |
| 6 | 6 | Noise-cancel Headphones | Electronics | 299.0 | 211.57 | 2025-01-14 |
| 7 | 7 | Python Cookbook | Books | 59.0 | 30.08 | 2025-09-15 |
| 8 | 8 | SQL Pocket Guide | Books | 39.9 | 22.14 | 2025-01-20 |
| 9 | 9 | 数据分析实战 | Books | 79.0 | 40.83 | 2024-12-15 |
| 10 | 10 | Clean Code | Books | 50.0 | 28.48 | 2025-03-13 |
| 11 | 11 | 统计学习方法 | Books | 99.0 | 70.22 | 2025-03-13 |
| 12 | 12 | Desk Lamp | Home | 45.0 | 24.99 | 2025-11-04 |
| 13 | 13 | Ceramic Mug | Home | 19.9 | 11.34 | 2025-12-02 |
| 14 | 14 | Throw Pillow | Home | 35.0 | 19.23 | 2024-06-29 |
| 15 | 15 | Wall Clock | Home | 99.0 | 47.98 | 2025-02-23 |
| 16 | 16 | Storage Box | Home | 29.9 | 15.06 | 2025-02-27 |
| 17 | 17 | Puzzle 1000pc | Toys | 129.0 | 59.53 | 2025-08-19 |
| 18 | 18 | Building Blocks | Toys | 199.0 | 110.19 | 2025-04-18 |
| 19 | 19 | RC Car | Toys | 359.0 | 208.55 | 2025-11-06 |
| 20 | 20 | Plush Panda | Toys | 89.0 | 43.14 | 2026-01-12 |
| # | product_idInt64 | priceFloat64 | bandString |
|---|---|---|---|
| 1 | 1 | 25.0 | low |
| 2 | 2 | 49.9 | low |
| 3 | 3 | 89.0 | mid |
| 4 | 4 | 199.0 | mid |
| 5 | 5 | 500.0 | high |
| 6 | 6 | 299.0 | high |
| 7 | 7 | 59.0 | mid |
| 8 | 8 | 39.9 | low |
| 9 | 9 | 79.0 | mid |
| 10 | 10 | 50.0 | mid |
| 11 | 11 | 99.0 | mid |
| 12 | 12 | 45.0 | low |
| 13 | 13 | 19.9 | low |
| 14 | 14 | 35.0 | low |
| 15 | 15 | 99.0 | mid |
| 16 | 16 | 29.9 | low |
| 17 | 17 | 129.0 | mid |
| 18 | 18 | 199.0 | mid |
| 19 | 19 | 359.0 | high |
| 20 | 20 | 89.0 | mid |
| 21 | 21 | 100.0 | mid |
| 22 | 22 | 249.0 | high |
| 23 | 23 | 699.0 | high |
| 24 | 24 | 15.0 | low |
| 25 | 25 | 39.9 | low |
| 26 | 26 | 200.0 | high |
| 27 | 27 | 12.5 | low |
| 28 | 28 | 49.9 | low |
| 29 | 29 | 159.0 | mid |
| 30 | 30 | 22.0 | low |