LeetCode 数据库查询题【Easy】：176. Second Highest Salary

发表于 更新于 分类于 阅读次数： Disqus：

Question

Table: Employee

1
2
3
4
5
6
7
8
+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | int  |
| salary      | int  |
+-------------+------+
id is the primary key column for this table.
Each row of this table contains information about the salary of an employee.

Write an SQL query to report the second highest salary from the Employee table. If there is no second highest salary, the query should report null.

The query result format is in the following example.

Example 1:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Input:
Employee table:
+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+
Output:
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200                 |
+---------------------+

Example 2:

1
2
3
4
5
6
7
8
9
10
11
12
13
Input:
Employee table:
+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
+----+--------+
Output:
+---------------------+
| SecondHighestSalary |
+---------------------+
| null                |
+---------------------+

My Answer

1
2
3
4
5
6
select ifnull(
    (select distinct salary
    from Employee
    order by salary desc 
    limit 1 offset 1), null
) as SecondHighestSalary