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Question
Formatted question description: https://leetcode.ca/all/181.html
Table: Employee
+-------------+---------+ | Column Name | Type | +-------------+---------+ | id | int | | name | varchar | | salary | int | | managerId | int | +-------------+---------+ id is the primary key column for this table. Each row of this table indicates the ID of an employee, their name, salary, and the ID of their manager.
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 1:
Input: Employee table: +----+-------+--------+-----------+ | id | name | salary | managerId | +----+-------+--------+-----------+ | 1 | Joe | 70000 | 3 | | 2 | Henry | 80000 | 4 | | 3 | Sam | 60000 | Null | | 4 | Max | 90000 | Null | +----+-------+--------+-----------+ Output: +----------+ | Employee | +----------+ | Joe | +----------+ Explanation: Joe is the only employee who earns more than his manager.
Algorithm
Two instance objects conduct internal communication through ManagerId and Id, and then the restriction is that one Salary is greater than the other.
Code
SQL
SELECT e1.Name FROM Employee e1
JOIN Employee e2 ON e1.ManagerId = e2.Id
WHERE e1.Salary > e2.Salary;
--
SELECT e1.Name FROM Employee e1, Employee e2
WHERE e1.ManagerId = e2.Id AND e1.Salary > e2.Salary;