对客户等级 tier 做独热编码。
tier 的取值固定为 bronze、silver、gold 三种，三列都要输出，列名为 tier_bronze、tier_silver、tier_gold，即使某个等级在表里一个客户都没有（那一列全为 0）。tier 为 null 的客户不生成额外的列，三列都为 0。customer_id 和这三列。输入
customers(customer_id, name, email, city, signup_date, tier)输出
列为 customer_id, tier_bronze, tier_silver, tier_gold，行顺序、列顺序不限。
customers shop/customers
| # | customer_idint64 | namestring | emailstring | citystring | signup_datedate | tierstring |
|---|---|---|---|---|---|---|
| 1 | 1 | Fang Wang | fang.wang@shop.io | Beijing | 2025-03-13 | silver |
| 2 | 2 | Dana Xu | dana.xu@mail.cn | null | 2025-02-17 | silver |
| 3 | 3 | Li Zhou | li.zhou@example.com | Guangzhou | 2025-10-07 | bronze |
| 4 | 4 | Ping Wang | ping.wang@example.com | null | 2025-05-23 | gold |
| 5 | 5 | Tom Zhang | tom.zhang@example.com | Shenzhen | 2025-06-26 | gold |
| 6 | 6 | 王芳 | user06@shop.io | Hangzhou | 2025-02-10 | gold |
| 7 | 7 | Victor Xu | victor.xu@example.com | Shanghai | 2025-12-05 | bronze |
| 8 | 8 | Dana Chen | dana.chen@example.com | Hangzhou | 2025-11-22 | bronze |
| 9 | 9 | Uma Chen | uma.chen@shop.io | Guangzhou | 2025-11-28 | null |
| 10 | 10 | Ivy Zhou | ivy.zhou@shop.io | Hangzhou | 2025-07-14 | gold |
| 11 | 11 | Mia Smith | mia.smith@mail.cn | Shanghai | 2025-04-28 | gold |
| 12 | 12 | Xin Yang | xin.yang@example.com | Chengdu | 2026-01-03 | silver |
| 13 | 13 | Xin Smith | xin.smith@mail.cn | Beijing | 2025-05-07 | silver |
| 14 | 14 | Zoe Xu | zoe.xu@mail.cn | Beijing | 2025-09-18 | silver |
| 15 | 15 | Fang Liu | fang.liu@shop.io | Guangzhou | 2025-08-05 | bronze |
| 16 | 16 | 杨磊 | user16@mail.cn | Shanghai | 2025-12-15 | silver |
| 17 | 17 | Ping Smith | ping.smith@mail.cn | null | 2025-08-11 | bronze |
| 18 | 18 | Oscar Zhou | oscar.zhou@example.com | Shanghai | 2025-11-17 | null |
| 19 | 19 | Kevin Liu | kevin.liu@mail.cn | Chengdu | 2026-02-03 | gold |
| 20 | 20 | Sara Wu | sara.wu@example.com | null | 2025-07-05 | gold |
| # | customer_idInt64 | tier_bronzeInt32 | tier_silverInt32 | tier_goldInt32 |
|---|---|---|---|---|
| 1 | 1 | 0 | 1 | 0 |
| 2 | 2 | 0 | 1 | 0 |
| 3 | 3 | 1 | 0 | 0 |
| 4 | 4 | 0 | 0 | 1 |
| 5 | 5 | 0 | 0 | 1 |
| 6 | 6 | 0 | 0 | 1 |
| 7 | 7 | 1 | 0 | 0 |
| 8 | 8 | 1 | 0 | 0 |
| 9 | 9 | 0 | 0 | 0 |
| 10 | 10 | 0 | 0 | 1 |
| 11 | 11 | 0 | 0 | 1 |
| 12 | 12 | 0 | 1 | 0 |
| 13 | 13 | 0 | 1 | 0 |
| 14 | 14 | 0 | 1 | 0 |
| 15 | 15 | 1 | 0 | 0 |
| 16 | 16 | 0 | 1 | 0 |
| 17 | 17 | 1 | 0 | 0 |
| 18 | 18 | 0 | 0 | 0 |
| 19 | 19 | 0 | 0 | 1 |
| 20 | 20 | 0 | 0 | 1 |
| 21 | 21 | 0 | 0 | 0 |
| 22 | 22 | 0 | 0 | 0 |
| 23 | 23 | 1 | 0 | 0 |
| 24 | 24 | 0 | 0 | 1 |
| 25 | 25 | 0 | 0 | 0 |
| 26 | 26 | 1 | 0 | 0 |
| 27 | 27 | 0 | 1 | 0 |
| 28 | 28 | 1 | 0 | 0 |
| 29 | 29 | 1 | 0 | 0 |
| 30 | 30 | 0 | 0 | 0 |
| 31 | 31 | 0 | 0 | 0 |
| 32 | 32 | 1 | 0 | 0 |
| 33 | 33 | 0 | 1 | 0 |
| 34 | 34 | 1 | 0 | 0 |
| 35 | 35 | 1 | 0 | 0 |
| 36 | 36 | 1 | 0 | 0 |
| 37 | 37 | 1 | 0 | 0 |
| 38 | 38 | 1 | 0 | 0 |
| 39 | 39 | 1 | 0 | 0 |
| 40 | 40 | 0 | 0 | 0 |
| 41 | 41 | 1 | 0 | 0 |
| 42 | 42 | 1 | 0 | 0 |
| 43 | 43 | 0 | 0 | 0 |
| 44 | 44 | 1 | 0 | 0 |
| 45 | 45 | 0 | 0 | 0 |
| 46 | 46 | 0 | 1 | 0 |
| 47 | 47 | 0 | 1 | 0 |
| 48 | 48 | 0 | 1 | 0 |
| 49 | 49 | 0 | 0 | 1 |
| 50 | 50 | 0 | 0 | 0 |