N(th) Highest Salary Query

I found a solution for finding the n(th) highest salary from the web :

SELECT * FROM Employee Emp1
WHERE (N-1) = (
           SELECT COUNT(DISTINCT(Emp2.Salary))
           FROM Employee Emp2
           WHERE Emp2.Salary > Emp1.Salary
           )

But I am unable to understand how the query is actually being executed, i.e. how the query is processing at each step, especially in the subquery where multiple alias of same table occur ->

WHERE Emp2.Salary > Emp1.Salary

And what is the comparison operator doing with this-

WHERE (N-1) = <subquery>

Can someone please help me out with it?

N(th) Highest Salary Query

2 Answers