Other Solutions

Here are three solution that worked for me, I found one mentioned above

# Using distinct ##

##############

SELECT distinct ee.*
FROM emp_manager ee
JOIN emp_manager eM ON ee.emp_no = eM.manager_no;

# Using Subqueries nested in WHERE  ##

###############################

SELECT ee.*
FROM emp_manager ee 
WHERE ee.emp_no IN  (SELECT distinct manager_no FROM emp_manager);

##  Using GROUP BY ############

############################

SELECT ee.emp_no, eM.manager_no
FROM emp_manager ee
JOIN emp_manager eM ON ee.emp_no = eM.manager_no
GROUP BY ee.emp_no;