Relationship & Schema Design

1. How many people work in Sales?
SELECT 
  count(*)
FROM
  employee e
  INNER JOIN
  department d
  ON e.department = d.id
WHERE
  e.department='Sales'

2. List the names of all employees assigned to the 'Plan Christmas party' project.
SELECT
  e.emp_name as Full_Name
FROM
  employee e
  JOIN 
  employee_project ep
  ON e.id = ep.emp_id
  JOIN
  project p
  ON ep.project_id = p.id
WHERE
  p.project_name='Plan Christmas party'
  
3. List the names of employees from the Warehouse department that are assigned to the 'Watch paint dry' project.
SELECT
  e.emp_name as Full_Name
FROM
  employee e
  INNER JOIN
  department d
  ON e.department = d.id
  JOIN 
  employee_project ep
  ON e.id = ep.emp_id
  JOIN
  project p
  ON ep.project_id = p.id
WHERE
  p.project_name='Watch paint dry' && e.department='Warehouse'

4. Which projects are the Sales department employees assigned to?
SELECT 
  e.emp_name as Full_Name
  ep.project_name
FROM
  employee e
  INNER JOIN
  department d
  ON e.department = d.id
  JOIN 
  employee_project ep
  ON e.id = ep.emp_id
WHERE
  e.department='Sales'

5.List only the managers that are assigned to the 'Watch paint dry' project.
SELECT
  e.emp_name as Full_Name
FROM
  department 
  JOIN 
  employee 
  ON department.manager = employee.id
  JOIN 
  employe_project ep
  ON employee.id = ep.emp_id
  JOIN
  project p
  ON ep.project_id = p.id
WHERE
  p.project_name='Watch paint dry'