We have two tables.

Table: department
Fields:
id Number (pk)
name Varchar(100)

Table: employee
Fields:
id Number (pk)
department_id Number
chief_id Number
name Varchar(100)
salary Number

Please write SQL queries for:

- Display a list of employees, who receive salary greater than the direct supervisor's salary
- Display a list of employees, who receive the maximum salary in his department
- Display a list of employees, who have no subordinates working in the same department
- Display a list of departments sorted by total salary of employees in it, descending