This code works as well and it is much simpler. Are there any cons I am not aware? SELECT e1.* FROM emp_manager e1 JOIN emp_manager e2 ON e1.emp_no = e2.manager_no GROUP BY e1.emp_no;

Hi Jose! Bravo! This is also a correct solution! Hope this helps. Best, Tsvetelin

haha yes, I was also thinking the same why are they not using GROUP BY

Hi I have tried using group by but i got the error code below. do you have any idea why? SELECT em1.* FROM emp_manager em1 JOIN emp_manager em2 ON em1.emp_no = em2.manager_id GROUP BY em1.emp_no; Error Code: 1055. Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'employees.em1.dept_no' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by Thanks