Query to Calculate the Max Value

FIRST MAX
SELECT MAX(SALARY)
FROM SALARY_TABLE
;
SECOND MAX

SELECT MAX(SALARY)
FROM SALARY_TABLE
WHERE SALARY < (SELECT MAX(SALARY)
FROM SALARY_TABLE)
;

N'TH MAX WITHOUT DUPLICATES

SELECT SALARY
FROM SALARY_TABLE A
WHERE 1 = ( SELECT COUNT(*)
FROM SALARY_TABLE B
WHERE B.SALARY >= A.SALARY)
;

-- N'TH MAX WITH DUPLICATES

SELECT DISTINCT SALARY
FROM SALARY A
WHERE 1 = ( SELECT COUNT(DISTINCT B.SALARY)
FROM SALARY_TABLE B
WHERE B.SALARY >= A.SALARY)