176.第二高的薪水
题目描述
Employee
表:
+-------------+------+
| Column Name | Type |
+-------------+------+
| id | int |
| salary | int |
+-------------+------+
在 SQL 中,id 是这个表的主键。
表的每一行包含员工的工资信息。
查询并返回 Employee
表中第二高的薪水 。如果不存在第二高的薪水,查询应该返回 null(Pandas 则返回 None)
。
查询结果如下例所示。
示例 1:
输入:
Employee 表:
+----+--------+
| id | salary |
+----+--------+
| 1 | 100 |
| 2 | 200 |
| 3 | 300 |
+----+--------+
输出:
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200 |
+---------------------+
示例 2:
输入:
Employee 表:
+----+--------+
| id | salary |
+----+--------+
| 1 | 100 |
+----+--------+
输出:
+---------------------+
| SecondHighestSalary |
+---------------------+
| null |
+---------------------+
SQL Schema
sql
DROP TABLE IF EXISTS Employee;
Create table If Not Exists Employee
(
id int,
salary int
);
Truncate table Employee;
insert into Employee (id, salary)
values ('1', '100');
insert into Employee (id, salary)
values ('2', '200');
insert into Employee (id, salary)
values ('3', '300');
答案
sql
SELECT IFNULL((SELECT DISTINCT salary FROM employee ORDER BY salary DESC LIMIT 1 OFFSET 1),
NULL) AS 'SecondHighestSalary';