What is the name of the department whose id is "d002"?

select dept_name
from departments
where dept_no="d002";

What employees were hired on June 22, 1988?

select * 
from employees
where hire_date=str_to_date("June 22, 1988","%M %d, %Y");

or

select * 
from employees
where hire_date='1988-06-22';

86 rows

What employees were hired before June 22, 1988?

select *  
from employees 
where hire_date<str_to_date("June 22, 1988","%M %d, %Y");

120106 rows

What employees work or have worked in the Finance department?

select first_name, last_name 
from employees, dept_emp, departments
where employees.emp_no=dept_emp.emp_no and
      departments.dept_no=dept_emp.dept_no and
      dept_name="Finance";

or

select first_name, last_name 
from employees join dept_emp using (emp_no) join departments using (dept_no) 
where dept_name="Finance";

17346 rows

See Explain Output Format

What employees currently work in the Finance department?

select first_name, last_name 
from employees, dept_emp, departments  
where employees.emp_no=dept_emp.emp_no and 
      departments.dept_no=dept_emp.dept_no and 
      dept_name="Finance" and 
      to_date>curdate();

or

select first_name, last_name 
from employees join dept_emp using (emp_no) join departments using (dept_no)
where dept_name="Finance" and
      to_date>curdate();

12437 rows

Who is the current manager of Mizuhito Kemmerer?

select e.first_name, e.last_name, de.to_date, dm.to_date, m.first_name, m.last_name
from employees e, employees m, dept_emp de, dept_manager dm
where e.emp_no=de.emp_no and
      m.emp_no=dm.emp_no and
      dm.dept_no=de.emp_no and
      e.first_name="Mizuhito" and
      e.last_name="Kemmerer" and
      de.to_date>curdate() and
      dm.to_date>curdate();

empty!!

It could be that he's not a current employee, or it could be that he doesn't have a manager.

List employees hired before Falck Mohua (should have been Mohua Falck).

select e2.*
from employees e1, employees e2
where e1.first_name="Mohua" and
      e1.last_name="Falck" and
      e1.hire_date>e2.hire_date;

But there are two Mohua Falck's. You can pick one, or try this:

select *
from employees
where hire_date>ALL(select hire_date from employees where first_name="Mohua" and last_name="Falck");

What employees work in the same department as Odysseas Ressouche?

Currently or ever?

If we ignore time:

select e2.first_name, e2.last_name
from employees e1, employees e2, dept_emp de1, dept_emp de2
where e1.emp_no=de1.emp_no and
      e2.emp_no=de2.emp_no and
      de1.dept_no=de2.dept_no and
      e1.first_name="Odysseas" and
      e1.last_name="Ressouche";

or

select e2.first_name, e2.last_name
from employees e1 join dept_emp de1 using (emp_no) join
     (employees e2 join dept_emp de2 using (emp_no)) using (dept_no)
where e1.first_name="Odysseas" and
      e1.last_name="Ressouche";

But if we require them to be working together currently:

select e2.first_name, e2.last_name
from employees e1, employees e2, dept_emp de1, dept_emp de2
where e1.emp_no=de1.emp_no and
      e2.emp_no=de2.emp_no and
      de1.dept_no=de2.dept_no and
      e1.first_name="Odysseas" and
      e1.last_name="Ressouche" and
      de1.to_date>curdate() and
      de2.to_date>curdate();

The answer is no one because Odysseas doesn't work here any more!!!

What managers manage an employee making more than 100,000?

Question: Should this be "currently manage", or should it be "have ever managed"?

This is the "have ever managed version:

select distinct m.first_name, m.last_name
from employees m, dept_manager dm, employees e, dept_emp de, salaries s
where m.emp_no=dm.emp_no and
      e.emp_no=de.emp_no and
      e.emp_no=s.emp_no and
      de.dept_no=dm.dept_no and
      s.salary > 100000;

or

select distinct m.first_name, m.last_name
from (employees m join dept_manager dm using (emp_no)) join 
     ((employees e join dept_emp de using (emp_no)) join salaries s using (emp_no))
     using (dept_no)
where s.salary > 100000;

228,382 rows without the distinct 24 rows with it

This is the currently manage version:

select distinct m.first_name, m.last_name
from employees m, dept_manager dm, employees e, dept_emp de, salaries s
where m.emp_no=dm.emp_no and
      e.emp_no=de.emp_no and
      e.emp_no=s.emp_no and
      de.dept_no=dm.dept_no and
      dm.to_date>curdate() and
      de.to_date>curdate() and
      s.to_date>curdate() and
      s.salary > 100000;

or

select distinct m.first_name, m.last_name
from (employees m join dept_manager dm using (emp_no)) join 
     ((employees e join dept_emp de using (emp_no)) join salaries s using (emp_no))
     using (dept_no)
where dm.to_date>curdate() and
      de.to_date>curdate() and
      s.to_date>curdate() and
      s.salary > 100000;

9 rows

Who is currently managing a department with Engineers in it?

Answer:

select m.first_name, m.last_name
from employees m, dept_manager dm, dept_emp de, employees e, titles
where m.emp_no=dm.emp_no and
      dm.dept_no=de.dept_no and
      de.emp_no=e.emp_no and
      titles.to_date>curdate() and 
      dm.to_date>curdate() and
      de.to_date>curdate() and
      titles.title like "%engineer%";

or

select distinct m.first_name, m.last_name
from (employees m join dept_manager dm using (emp_no)) join
     (dept_emp de join employees e using (emp_no) join titles using (emp_no))
     using (dept_no)
where titles.to_date>curdate() and 
      dm.to_date>curdate() and
      de.to_date>curdate() and
      titles.title like "%engineer%";