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.
感觉难在如何返回null，而且相同的薪水排在同一位。
AC代码：
select (select distinct salary as second_highest_salary from Employee order by salary desc limit 1 offset 1)
以下：
注意上图那一行是null。
LeetCode Second Highest Salary
原文：http://blog.csdn.net/u012925008/article/details/45000249
