Your query works as it is.
Simpler would be
SELECT TOP 1 * FROM AVI_02Mar2016 ORDER BY SALARY DESC
If you are trying to get the maximum salary from a set of tables then you can use a CTE
;WITH AllTables AS
(
SELECT TOP 1 * FROM AVI_02Mar2016 ORDER BY SALARY DESC
UNION ALL
SELECT TOP 1 * FROM AVI_02Apr2016 ORDER BY SALARY DESC
)
SELECT TOP 1 * FROM AllTables ORDER BY SALARY DESC
Even better would be to have a single table
AVI
and have an extra column for the date.