How to write this complex SQL query?

Question

I need to find the names of aircraft such that all pilots certified to operate them earn more than 60000.

Query I wrote:

select aname 
from employee join certified
on employee.eid=certified.eid
join aircraft
on certified.aid=aircraft.aid
where salary>60000;

But it returns aname if there is any pilot with more than 60000 salary,difficult part is that i need to find if all pilots earn more than 60000 only then the aname is displayed.

Answer 1

You can just look for the opposite case - that no pilots earn less than 60,000:

SELECT
    aname
FROM
    Aircraft A
WHERE
    NOT EXISTS
    (
        SELECT *
        FROM Certified C
        INNER JOIN Employee E ON
            E.eid = C.eid AND
            E.salary < 60000
        WHERE C.aid = A.aid
    )

Answer 2

SELECT aname FROM Aircraft where NOT EXISTS (SELECT eid FROM Employee AS e INNER JOIN Certified AS c ON c.eid=e.eid WHERE salary<60000 AND aid=Aircraft.aid)

Answer 3

从存在飞机的地方选择一个名字（从经过认证的C内联结中选择*雇员E ON e.eid = C.eid和E.salary> 60000 W.E C.aid = A.aid）