如何对具有相同列名作为主键但不同值的表执行 UNION

Question

这是两个表： 输入：

Employees table:
+-------------+----------+
| employee_id | name     |
+-------------+----------+
| 2           | Crew     |
| 4           | Haven    |
| 5           | Kristian |
+-------------+----------+
Salaries table:
+-------------+--------+
| employee_id | salary |
+-------------+--------+
| 5           | 76071  |
| 1           | 22517  |
| 4           | 63539  |
+-------------+--------+

我想要一个像你如何执行连接但使用联合的输出。

联合的输出应如下所示：

employee_id   | name       | salary 
2              crew.        null 
4.             haven.       63539 
5.             Kristian     76071
1.             null.        22517

并发布工会我想执行选择，通过选择没有姓名或没有薪水的员工的employee_id

目前我正在处理的查询：

select * from 
(select employee_id, name, null as salary from employees 
union all 
select employee_id, null as name, salary from salaries) 
as emp 
where name is null or salary is null

结果如下：

{"headers": ["employee_id", "name", "salary"], "values": [[2, "Crew", null], [4, "Haven", null], [5, "Kristian", null], [5, null, 76071], [1, null, 22517], [4, null, 63539]]}

如果使用这个查询：

select * from (select employee_id, name from employees union all select employee_id, salary from salaries) as emp

结果如下：

{"headers": ["employee_id", "name"], "values": [[2, "Crew"], [4, "Haven"], [5, "Kristian"], [5, "76071"], [1, "22517"], [4, "63539"]]}

Answer 1

这是一个完整的连接：

Select coalesce(e.employeeid, s.employeeid) employed
       e.name, e.salary
From employees e full join
     Salaries s
     On e.employeeid = s.employeeid