How to find maximum salary in the SalaryDB? code example

Example: sql highest salary by location

/*  Highest salary by Department/Location   */
SELECT e.ename, e.sal, e.deptno, d.loc
FROM emp e
JOIN dept d
ON e.deptno = d.deptno
WHERE e.sal in
( 	
  	select max(sal) 
  	from emp 
  	group by deptno
)