select e.emp_no,e.first_name,e.last_name,eb.btype,s.salary,
(case btype when 1 then round(0.1*s.salary,1)
when 2 then round(0.2*s.salary,1)
else round(0.3*s.salary,1)
end) as bonus 
from employees e
left join emp_bonus eb on e.emp_no=eb.emp_no
join salaries s on eb.emp_no=s.emp_no
where s.to_date='9999-01-01' 
order by emp_no