Second Highest Salary Leetcode

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.

找到第二大的工资值。

找第几大的，最简单的思路就是通过ORDER BY 和 LIMIT组合进行查找。

所以开始答案是这样的：

SELECT distinct Salary FROM Employee Order by Salary desc Limit 1,1

但是这个解法不能满足如果没有值的话返回null这个要求，所以要加上判断语句，即：

SELECT IFNULL((SELECT distinct Salary FROM Employee Order by Salary desc Limit 1,1),NULL);

但是，因为这道题目要求的是寻找的2大的值，而不是第n大的值，所以也可以使用max来完成，并且max（）函数如果找不到合适的值就会返回null，所以比较简单。具体SQL语句如下：

SELECT MAX(SALARY) FROM EMPLOYEE WHERE SALARY<(SELECT MAX(SALARY) FROM EMPLOYEE);