LeetCode_176_Second Highest Salary.sql

-- 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 query should return 200 as the second highest salary. If there is no second highest salary, then the query should return null.

-- +---------------------+
-- | SecondHighestSalary |
-- +---------------------+
-- | 200                 |
-- +---------------------+

select distinct(Salary) as SecondHighestSalary from Employee  union select null  order by SecondHighestSalary desc limit 1 offset 1;