176 Second Highest Salary 第二高的薪水
Description:
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 |
+---------------------+
题目描述:
编写一个 SQL 查询，获取 Employee 表中第二高的薪水（Salary） 。
+----+--------+
| Id | Salary |
+----+--------+
| 1 | 100 |
| 2 | 200 |
| 3 | 300 |
+----+--------+
例如上述 Employee 表，SQL查询应该返回 200 作为第二高的薪水。如果不存在第二高的薪水，那么查询应返回 null。
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200 |
+---------------------+
思路:
DISTINCT
LIMIT
IFNULL
代码:
MySQL:
# Write your MySQL query statement below
SELECT IFNULL((SELECT DISTINCT(Salary) FROM Employee ORDER BY Salary DESC LIMIT 1, 1), NULL) AS SecondHighestSalary
