181. Employees Earning More Than Their Managers

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Link

Write an SQL query to find the employees who earn more than their managers.

Return the result table in any order.

The query result format is in the following example.

Example

풀이

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📌 Self Join 문제가 헷갈릴 때는 각 테이블과 컬럼에 대해서 alias를 명확히 붙여주자

1. SELF JOIN 으로 manager 테이블 생성
   혼동 방지를 위해서 각 컬럼의 alias를 명확히 붙여주고 테이블을 확인하자.

SELECT employee.name AS employee_name
     , employee.salary AS employee_salary
     , manager.name AS manager_name
     , manager.salary AS manager_salary
FROM employee
    INNER JOIN employee AS manager ON employee.managerID = manager.id

2. employee salary가 manager salary 보다 높은 경우 출력하는 조건 생성

WHERE WHERE employee.salary > manager.salary

3. 최종 SELECT 쿼리 조건 정리

SELECT employee.name AS Employee
FROM employee
    INNER JOIN employee AS manager ON employee.managerID = manager.id
WHERE employee.salary > manager.salary

My Answer

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SELECT employee.name AS Employee
FROM employee
    INNER JOIN employee AS manager ON employee.managerID = manager.id
WHERE employee.salary > manager.salary