Difference Between Rank and DenseRank in Sql

Hi,

Here is the differnce between  Rank() and DenseRank() function

Consider Below  Table Employee Which is ordered by salary

Table Name: Employee

EmpId         Name         Salary

 1  John       100

 2               Jenny           170

 3               Mac             170

 4               Millon 350

Here is the query to rank employee by salary

Select *, Dense_RANK() over(order by Salary) As DenseRank,RANK() over(order by Salary) As Rank From Employee  

Now the tablewill be

EmpId           Name            Salary       Rank     DenseRank

 1                John             100          1             1

 2                 Jenny             170          2             2

 3                 Mac                170         2             2

 4                 Millon  350         4             3

Dense Rank last value will be the total unique value in table