display the second highest salary employee code example

Example 1: sql select second max

Both options you find max as a subset and then exclude from main select
sql> SELECT MAX( col ) FROM table
 	WHERE col < ( SELECT MAX( col ) FROM table);
sql> SELECT MAX(col) FROM table 
WHERE col NOT IN (SELECT MAX(col) FROM table);

Example 2: how to get employee having maximum experience in mysql

select max(salary), dept_id from employee where salary not in(select max(salary) from employee) group by dept_id;