What is the difference between DenseRank and Rank function in oracle?

RANK gives you the ranking within your ordered partition. Ties are assigned the same rank, with the next ranking skipped. So, if you have 3 items at rank 2, the next rank listed would be ranked 5.

DENSE_RANK again gives you the ranking within your ordered partition, but no ranks are skipped if there are ranks with multiple items.

E.g:- Suppose we have a table called SalaryDetails as shown below

Query:- Select * from SalaryDetails;

O/P:-

Id	EmployeeDetailsId	Salary
101	1	2000.50
102	2	3050.50
103	3	4000.00
104	4	2000.50
105	5	2000.50

Condition:- Fetch the records from the table and assign the rank to the EmployeeDetailsId on the basis of salary ascending to descending order.

Query:- Select EmployeeDetailsId,Salary,

                            DENSE_RANK() Over(Order By Salary) as DenseRank_Salary,

                           Rank() Over(Order by Salary) as Rank_Salary

              from SalaryDetails;

O/P:-

EmployeeDetailsId	Salary	DenseRank_Salary	Rank_Salary
1	2000.50	1	1
5	2000.50	1	1
4	2000.50	1	1
2	3050.50	2	4
3	4000.50	3	5