Query 1

   SELECT MAX(salary) FROM employee
                                       WHERE salary NOT IN
 ( SELECT MAX(salary) FROM employee)


Query 2 

     SELECT MAX(salary) FROM employee
                                         WHERE salary <
   ( SELECT MAX(salary) FROM employee)

Query 3 (for SQL Server)


    SELECT MIN (salary) FROM employee
                                       WHERE salary in
(SELECT TOP 2 (salary) FROM employee
                                 ORDER BY salary DESC)