Tables: department, dept_emp, dept_manager, employees, salaries, titles

department (columns): dept_no, dept_name

dept_emp (columns): emp_no, dept_no, from_date, to_date

dept_manager (columns): emp_no, dept_no, from_date, to_date

employees (columns): emp_no, birth_date, first_name, last_name, gender, hire_date

salaries (columns): emp_no, salary, from_date, to_date

titles (columns): emp_no, title, from_date, to_date

I need help with writing SQL queries for the questions below. The information about the tables in the SQL database are listed above.

1) What queries are needed for the following:

a) What is the ratio of salary of female / male in the company? Do we have equal pay in this company?

b) Who was the first department manager?

c) Who was the first department manager?

d) Is there any department which has more than one manager?

e) Is there any employee who does not work for any department?