employees-earning-more-than-their-managers.sql

# Time: O(n^2)
# Space: O(1)
# 
# The Employee table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.
# 
# +----+-------+--------+-----------+
# | Id | Name  | Salary | ManagerId |
# +----+-------+--------+-----------+
# | 1  | Joe   | 70000  | 3         |
# | 2  | Henry | 80000  | 4         |
# | 3  | Sam   | 60000  | NULL      |
# | 4  | Max   | 90000  | NULL      |
# +----+-------+--------+-----------+
# Given the Employee table, write a SQL query that finds out employees who earn more than their managers. For the above table, Joe is the only employee who earns more than his manager.
# 
# +----------+
# | Employee |
# +----------+
# | Joe      |
# +----------+
#

# Time: O(n^2)
# Space: O(n)
# Write your MySQL query statement below
SELECT e.Name AS Employee  FROM Employee e LEFT JOIN Employee b
       ON e.ManagerId=b.Id
       WHERE e.Salary > b.Salary

# Time: O(n^2)
# Space: O(1)      
# Write your MySQL query statement below
SELECT Name AS Employee 
    FROM Employee e 
    WHERE e.ManagerId IS NOT NULL AND e.Salary > (SELECT Salary 
                          FROM Employee 
                          WHERE e.ManagerId = Id)