Source

• leetcode: Second Highest Salary

Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+
For example, given the above Employee table, the second highest
salary is 200. If there is no second highest salary, then the query
should return null.

MySQL

select Max(Salary)
from Employee
where Salary < (select Max(Salary) from Employee)