SQL Query help: co-workers and employees from one query
select u.id, u.username, u.fullName
from user u
join user_employment e1 on e1.employee_id = u.id
join user_employment e2 on e2.employer_id = e1.employer_id
where (e1.end &gt;= NOW() or e1.end is NULL)
       and (e2.end &gt;= NOW() or e2.end is NULL)
       and e2.employee_id = 2
       and e1.status = "confirmed"
       and e2.status = "confirmed"
       and u.id &lt;&gt; 2
group by u.id;


http://sqlfiddle.com/#!9/b13e6/4

Find the employer of a given user and then find all (other) employees of that employer. Do not use left joins unless you need them (you do not in this case).