自连接与 set_alias
中等
25-duckdb-rel-only DuckDB Relational 专属
self-joinset-aliasleft-joinhierarchy
列出每个员工和他的直属经理的名字。
- 经理由
manager_id 指向同一张表里的 emp_id。
- 每个员工都要输出:没有经理(
manager_id 为 null),或者 manager_id 在表里找不到对应员工时,manager_name 为 null。
- 员工可能重名,要按 id 匹配,不能按名字。
输入
employees(emp_id, name, dept_id, manager_id, hire_date, salary, title, email)(已绑定为 relation)
输出
列为 emp_id, emp_name, manager_name,每个员工一行,行顺序不限。
输入表 (case base,共 2 个 case:base、edge)
期望输出 (case base,行顺序不限)
| # | emp_idInt64 | emp_nameString | manager_nameString |
| 1 |
2 |
Leo Wang |
Grace Liu |
| 2 |
3 |
Sara Chen |
Grace Liu |
| 3 |
4 |
Lucas Zhang |
Leo Wang |
| 4 |
5 |
Mia Zhao |
Leo Wang |
| 5 |
6 |
Kevin Wu |
Sara Chen |
| 6 |
7 |
Lily Xu |
Lucas Zhang |
| 7 |
8 |
Tom Huang |
Lucas Zhang |
| 8 |
9 |
Liam Zhou |
Lucas Zhang |
| 9 |
10 |
Nina Yang |
Lucas Zhang |
| 10 |
11 |
Oscar Lin |
Tom Huang |
| 11 |
12 |
Linda Ma |
Mia Zhao |
| 12 |
13 |
Eric Sun |
Mia Zhao |
| 13 |
14 |
Ivy He |
Mia Zhao |
| 14 |
15 |
Lei Gao |
Linda Ma |
| 15 |
16 |
Hao Guo |
Lily Xu |
| 16 |
17 |
Fang Luo |
Lily Xu |
| 17 |
18 |
Jun Liang |
Hao Guo |
| 18 |
19 |
Dana Song |
Kevin Wu |
| 19 |
20 |
Victor Tang |
Kevin Wu |
| 20 |
21 |
Wen Han |
Kevin Wu |
| 21 |
22 |
Lu Feng |
Kevin Wu |
| 22 |
23 |
Yan Deng |
Wen Han |
| 23 |
24 |
Zoe Cao |
Grace Liu |
| 24 |
25 |
Ping Peng |
Tom Huang |
| 25 |
26 |
Qing Xie |
Tom Huang |
| 26 |
27 |
Rui Lu |
Sara Chen |
| 27 |
28 |
Uma Jiang |
Leo Wang |
| 28 |
29 |
Xin Cai |
Mia Zhao |
| 29 |
30 |
Bob Pan |
Lucas Zhang |
| 30 |
31 |
Chen Du |
Lily Xu |
| 31 |
32 |
Amy Yu |
Kevin Wu |
| 32 |
33 |
Larry Ren |
Leo Wang |
| 33 |
34 |
Wei Shi |
Linda Ma |
| 34 |
35 |
Zhang Min |
Tom Huang |
| 35 |
36 |
王磊 |
Kevin Wu |
| 36 |
37 |
李静 |
Xin Cai |
| 37 |
38 |
Henry Kong |
Hao Guo |
| 38 |
39 |
Logan Bai |
Bob Pan |
| 39 |
40 |
Sophie Fan |
Amy Yu |
| 40 |
1 |
Grace Liu |
null |
共 40 行
参考答案 · 自连接与 set_alias