Найти различные значения из сгенерированного набора результатов в SQL

Question

Два утверждения утверждения объединяются вместе с несколькими внутренними соединениями. Просто нужно выяснить отдельные элементы из этих наборов результатов.

Я мог бы написать отчет при выборе столбцов, но это не то, что я хочу.

SELECT 
    employeeid, employeename 
FROM 
    employee AS emp   
INNER JOIN 
    department AS dep ON emp.employeeid = dep.employeeid   
INNER JOIN 
    company AS comp ON emp.companyid = comp.companyid 

UNION 

SELECT 
    employeeid, employeename 
FROM 
    employer AS emp   
INNER JOIN 
    category AS cat ON emp.employeeid = cat.employeeid   
INNER JOIN 
    business AS busi ON emp.companyid = busi.companyid 

Answer 1

SELECT DISTINCT employeeid, employeename 
FROM 
(
    SELECT 
     employeeid, employeename 
    FROM 
     employee AS emp   
    INNER JOIN 
     department AS dep ON emp.employeeid = dep.employeeid   
    INNER JOIN 
     company AS comp ON emp.companyid = comp.companyid 

    UNION 

    SELECT 
     employeeid, employeename 
    FROM 
     employer AS emp   
    INNER JOIN 
     category AS cat ON emp.employeeid = cat.employeeid   
    INNER JOIN 
     business AS busi ON emp.companyid = busi.companyid 
) AS t