#2nd Most highest salary using Limit & Order By
SELECT Salary FROM (SELECT Salary FROM Employee ORDER BY salary DESC LIMIT 2) AS Emp ORDER BY salary LIMIT 1;#2nd Most highest salary using Group By, Order By & Limit clause
SELECT sal FROM emp GROUP BY sal ORDER BY sal DESC LIMIT 1, 1;#2nd Most highest salary using dense_rank()
SELECT sal
FROM (SELECT dense_rank() over(ORDER BY sal DESC) AS R, sal FROM emp) employee
WHERE R = 2;#Corelated Subquery
SELECT Id, Salary
FROM Employee e
WHERE 2=(SELECT COUNT(DISTINCT Salary) FROM Employee p
WHERE e.Salary<=p.Salary)