Doctors Earning More Than Their Supervisors

Write an SQL query to find the doctors who earn more than their supervisors.

Input :-

Doctor table :-
ID is the Primary Key column for the Doctors table.

ID	Name	Compensation	Supervisor_ID
1	Kiran	60000	3
2	Prakash	70000	4
3	Rajesh	50000	null
4	Shekar	80000	null

Output :-

Doctor

Kiran

Query :-

select d2.name as Doctor
from Doctor d1, Doctor d2
where d2.Supervisor_ID=d1.ID and d2.compensation>d1.compensation;

Explanation : - 

This SQL query selects the names of doctors (represented by the name attribute in the Doctor table) who have a supervisor (represented by the Supervisor_ID attribute in the Doctor table) with a higher compensation than themselves.

The query achieves this by joining the Doctor table with itself (using aliases d1 and d2) on the condition that d2.Supervisor_ID matches d1.ID. This means that d2 is a doctor who reports to d1.

The where clause then applies a filter condition to select only those doctors (d2) whose compensation is greater than their supervisor's (d1).

The result of the query is a list of doctors who have higher compensation than their supervisors.