SELECT (SELECT MAX (Salary)
FROM Employees) AS S1,
(SELECT MAX (Salary)
FROM Employees
WHERE Salary NOT IN (S1)) AS S2,
(SELECT MAX (Salary)
FROM Employees
WHERE Salary NOT IN (S1, S2)) AS S3,
...
(SELECT MAX (Salary)
FROM Employees
WHERE Salary NOT IN (S1, S2, ... S[n-1])) AS Sn
FROM DummyTable