RANKING Functions

ROW_NUMBER () OVER ([<partition_by_clause>] <order_by_clause>)
Returns the sequential number of a row within a partition of a result set, starting at 1 for the first row in each partition.

RANK () OVER ([<partition_by_clause>] <order_by_clause>)
Returns the rank of each row within the partition of a result set.

DENSE_RANK () OVER ([<partition_by_clause>] <order_by_clause>)
Returns the rank of rows within the partition of a result set, without any gaps in the ranking.

NTILE (integer_expression) OVER ([<partition_by_clause>] <order_by_clause>)
Distributes the rows in an ordered partition into a specified number of groups.

 EXAMPLES:

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Suppose you are having table like below

Example :1

select ROW_NUMBER() over(order by salary)ROW_NUMBER,RANK()over(order by salary)

RANK,DENSE_RANK() over(order bysalary)DENSE_RANK,* from emp

Example :2

select ROW_NUMBER()over (order by empname)ROW_NUMBER,RANK()over (order byempname)RANK,DENSE_RANK()over (order by empname)DENSE_RANK,* from emp

Example :3

select ROW_NUMBER()over(partition by empname order by salary)ROW_NUMBER,RANK()

over(partitionby empname order by salary)RANK,DENSE_RANK()over(partition by

 empname order bysalary)DENSE_RANK,* from emp

Example :4

select ROW_NUMBER()over(partition by salary order by empname)ROW_NUMBER,RANK()

over(partitionby salary order by empname)RANK,DENSE_RANK()over(partition by 

salary order byempname)DENSE_RANK,* from emp

Example :5

select ROW_NUMBER()over(partition by empname order by empname)ROW_NUMBER,RANK()

over(partitionby empname order by empname)RANK,DENSE_RANK()

over(partition by empname order byempname)DENSE_RANK,* from emp

Example :6

select ROW_NUMBER()over(partition by salary order by salary)

ROW_NUMBER,RANK()over(partitionby salary order by salary)

RANK,DENSE_RANK()over(partition by salary order bysalary)

DENSE_RANK,* from emp