text: -- 1. List the following details of each employee: employee number, last name, first name, gender, and salary.
  SELECT employees.emp_no, employees.last_name, employees.first_name, employees.gender, salaries.salary
  FROM employees
  JOIN salaries
  ON employees.emp_no = salaries.emp_no;
  
  -- 2. List employees who were hired in 1986.
  SELECT emp_no AS id, first_name, last_name, hire_date
  FROM employees
  WHERE hire_date BETWEEN '1/1/86' AND '12/31/86';
  
  -- 3. List the manager of each department with the following information: department number, department name, the manager's employee number, last name, first name, and start and end employment dates.
  SELECT departments.dept_no, departments.dept_name, dept_manager.emp_no, employees.last_name, employees.first_name, dept_manager.from_date, dept_manager.to_date
  FROM departments
  JOIN dept_manager
  ON departments.dept_no = dept_manager.dept_no
  JOIN employees 
  ON dept_manager.emp_no = employees.emp_no;
  
  -- 4. List the department of each employee with the following information: employee number, last name, first name, and department name.
  SELECT dept_emp.emp_no, employees.last_name, employees.first_name, departments.dept_name
  FROM dept_emp
  JOIN employees
  ON dept_emp.emp_no = employees.emp_no
  JOIN departments
  ON dept_emp.dept_no = departments.dept_no;
  
  -- 5. List all employees whose first name is "Hercules" and last names begin with "B."
  SELECT first_name, last_name
  FROM employees
  WHERE first_name = 'Hercules'
  AND last_name LIKE 'B%';
  
  -- 6. List all employees in the Sales department, including their employee number, last name, first name, and department name.
  SELECT dept_emp.emp_no, employees.last_name, employees.first_name, departments.dept_name
  FROM dept_emp
  JOIN employees
  ON dept_emp.emp_no = employees.emp_no
  JOIN departments
  ON dept_emp.dept_no = departments.dept_no
  WHERE departments.dept_name = 'Sales';
  
  -- 7. List all employees in the Sales and Development departments, including their employee number, last name, first name, and department name.
  SELECT dept_emp.emp_no, employees.last_name, employees.first_name, departments.dept_name
  FROM dept_emp
  JOIN employees
  ON dept_emp.emp_no = employees.emp_no
  JOIN departments
  ON dept_emp.dept_no = departments.dept_no
  WHERE departments.dept_name = 'Sales' 
  OR departments.dept_name = 'Development';
  
  -- 8. In descending order, list the frequency count of employee last names, i.e., how many employees share each last name.
  SELECT last_name,
  COUNT(last_name) AS "frequency"
  FROM employees
  GROUP BY last_name
  ORDER BY
  COUNT(last_name) DESC;