Employee Manager Report - Sql Server

Question

I have the below table

empid   empname     managerID
1          A          NULL
2          B           1
3          C           1
4          D           2
         


        

Answer 1

Self join the table

case 1: all employees who have managers

select e1.empname employee, e2.empname manager
from employee e1
join employee e2 on e1.managerId = e2.empid
order by e2.name,e1.name

case 2: all employees who have managers or not

select e1.empname employee, COALESCE(e2.empname,'none') manager
from employee e1
left join employee e2 on e1.managerId = e2.empid
order by e2.name,e1.name