text: drop table if Exists Employee;
  Create table If Not Exists Employee (Id int, Name varchar(255), Salary int, ManagerId int);
  Truncate table Employee;
  insert into Employee (Id, Name, Salary, ManagerId) values ('1', 'Joe', '70000', '3');
  insert into Employee (Id, Name, Salary, ManagerId) values ('2', 'Henry', '80000', '4');
  insert into Employee (Id, Name, Salary, ManagerId) values ('3', 'Sam', '60000', NULL);
  insert into Employee (Id, Name, Salary, ManagerId) values ('4', 'Max', '90000', NULL);