为什么Apache Drill选择具有不同表格的相同名称的列

Question

我有一个PostgreSQL数据库链接到一个Drill实例。

每当我试图加入两个表都有一列name和每当我想选择此name钻选择错误的name列。我究竟做错了什么？

鉴于以下两个表：

Department 
| id | name | 
|----|------| 
| 1 | A | 
| 2 | B | 

Employee 
| id | name | dept | salary | 
|----|------|------|--------| 
| 1 | U | 1 | 100 | 
| 2 | V | 1 | 75 | 
| 3 | W | 1 | 120 | 
| 4 | X | 2 | 95 | 
| 5 | Y | 2 | 140 | 
| 6 | Z | 2 | 55 | 

---

运行

select employee.name, employee.salary 
from employee 
inner join department on employee.dept = department.id 
where department.name = 'A' 

回报

| name | salary | 
|------|--------| 
| A | 100 | 
| A | 75 | 
| A | 120 | 

---

茹nning

select dept.name, employee.salary 
from employee 
inner join department on employee.dept = department.id 
where department.name = 'A' 

回报

| name | salary | 
|------|--------| 
| null | 100 | 
| null | 75 | 
| null | 120 | 

---

什么工作，但似乎很愚蠢对我来说，就是：

select dept.name, employee.salary 
from employee 
inner join (select id, name as deptname from department) as department on employee.dept = department.id 
where department.deptname = 'A' 

Answer 1

这似乎是因为你用

select dept.name, [...]

但是您从未为表department（department AS dept）分配了别名。因此

select department.name, [...]

应该得到你正在寻找的价值。