员工部门的唯一名称

debugcn 发表于 Dev

Statguy 用户

我有一个员工数据库，员工多次出现。

同一员工的某些实例具有员工部门，而在其他一些情况下，缺少员工部门。为此，我需要找到与员工部门不同的员工姓名。
有些员工根本没有任何员工部门。为此，我只需要找到不同的员工姓名。

我的查询：

------for each unique employee, find department
--select columns
select 
  a.employee_name,b.employee_dept
from
  --unique employee names
  (
   select 
     distinct employee_name 
   from 
     employeeDB 
   where 
     employee_name is not null and employee_name != ''
   order by employee_name asc
  ) as a,
  --employee name and employee dept sorted
  (
  select 
     employee_name,employee_dept 
   from 
     employeeDB 
   where employee_name is not null and employee_name != ''
   order by employee_name asc, employee_dept desc
  ) as b
--condition for join
where
  a.employee_name = b.employee_name
order by a.employee_name asc, b.employee_dept desc
limit 1000

我不确定为什么结果没有返回唯一的结果。我得到类似于下面的结果

Name  Dept
A     DepA
A     DepB
A   
B     DepA
B   
C     DepZ
D   
E

于尔根

这将获得所有唯一的名称（通过将其分组）并employee_dept获取每个字母可以找到的（字母顺序）最高的名称

select employee_name, max(employee_dept) as dept
from employeeDB 
where employee_name is not null and employee_name != ''
group by employee_name
order by employee_name asc
limit 1000

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