There many ways to find nth highest salary.

 

Consider below EMP table structure

EMPNNO EMPNAME SALARY DEPTNO
10 Bill 12000 5
11 Solomon 10000 5
12 Susan 10000 5
13 Wendy 9000 1
14 Benjamin 7500 1
15 Tom 7600 1
16 Henry 8500 2
17 Robert 9500 2
18 Paul 7700 2
19 Dora 8500 3
20 Samuel 6900 3
21 Mary 7500 3
22 Daniel 6500 4
23 Ricardo 7800 4
24 Mark 7200 4

List of all employees,salary,rank in descending order

SALARY EMPNO RANK
12000 10 1
10000 11 2
10000 12 2
9000 13 3
7500 14 4
7600 15 5
8500 16 5
9500 17 6
7700 18 7
8500 19 8
6900 20 9
7500 21 9
6500 22 10
7800 23 11
7200 24 12

1) Find highest salary/salaries using DENSE_RANK() function

select * from (select empno,salary,dense_rank() over(order by salary desc) as rk from emp) where rk = 1;

EMPNO                SALARY               RK
———-      ———-       ———-
10                            12000                     1

2) Find 2nd highest salary/salaries using DENSE_RANK() function

select * from (select empno,salary,dense_rank() over(order by salary desc) as rk from emp) where rk = 2;

EMPNO                       SALARY              RK
———-           ———-         ———-
11                                      10000               2
12                                     10000               2

If you replace 2 with N in above query it will provide Nth highest salary/salaries.

3. Find 2nd highest salary using ROW_NUMBER() function

select * from (select empno, salary, row_number() over(order by salary desc) rk from emp order by salary desc ) where rk = 2;

EMPNO                     SALARY              RK
———-           ———-         ———-
11                                10000                    2

Note that this query will not give multiple records if there are employees with same salaries ( compare query (2) and (3) )

4. Find 2nd highest salary using ROWNUM

select * from (select empno, salary,rownum rk from emp order by salary desc) where rk = 2;

EMPNO                           SALARY          RK
———-           ———-         ———-
11                                        10000               2

Note that this query also will not give multiple records if there are employees with same salaries ( compare query (2) and (4) )

Conclusion :- Use DENSE_RANK, ROW_NUMBER(), ROWNUM with respect to the requirement. As per my experience query with ROW_NUMBER() is most appropriate and good for performance.

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