Example:
my table ‘salary_table’ with name and salary fields
id name salary
1 vasanthan 300
2 sunil 300
3 nasar 200
4 raja 100
5 Raina 400
6 Haier 600
7 shaji 400
for getting second highest salary use the following queries
SELECT MAX( salary ) FROM salary_table WHERE salary NOT IN (SELECT MAX( salary ) FROM salary_table)
// output : 400
select distinct salary from salary_table order by salary desc limit 1,1
// output : 400
for getting third higest salary you can use the following query
select distinct salary from salary_table order by salary desc limit 2,1
// output : 300