리트코드(leetcode) 문제풀이 : Second Highest Salary (10/23)

Table: Employee

Column Name	Type
id	int
salary	int

id is the primary key (column with unique values) for this table.
Each row of this table contains information about the salary of an employee.

Write a solution to find the second highest distinct salary from the Employee table. If there is no second highest salary, return null (return None in Pandas).

The result format is in the following example.

Example 1:

Input:
Employee table:

id	salary
1	100
2	200
3	300

Output:

SecondHighestSalary
200

Example 2:

Input:
Employee table:

id	salary
1	100

Output:

SecondHighestSalary
null

Employee 테이블에서 두 번째로 높은 고유한 급여를 찾는 문제. 두 번째로 높은 급여가 없으면 null을 반환한다는 조건이 있다.

select max(salary) as SecondHighestSalary
from employee
where salary < (select max(salary)
				from employee);

• select max(salary) as SecondHighestSalary :
  테이블에서 가장 높은 급여를 찾는다.
• where 절 :
  salary < (select max(salary) from employee :
  가장 높은 급여보다 작은 급여를 where 조건으로 찾는다.