SELECT
    name
FROM
    Customer
WHERE
    referee_id <> 2
    OR
    referee_id IS NULL

SELECT
    E.name,
    B.bonus
FROM
    Employee E
    LEFT JOIN Bonus B
    ON E.empId = B.empId
WHERE
    B.bonus < 1000
    OR
    B.bonus IS NULL

SELECT 
    E1.name
FROM 
    Employee E1 
    LEFT JOIN Employee E2
    ON E1.id = E2.managerId
GROUP BY
    E1.id
HAVING
    COUNT(E1.id) >= 5