SQL PERCENT_RANK Function

The SQL Server PERCENT_RANK is one of the Analytic functions, which will calculate the relative rank of each row. This function will return the rank from a range of values greater than 0 and less than 1. The basic syntax of the SQL PERCENT_RANK is:

SELECT PERCENT_RANK() 
               OVER (
                      PARTITION_BY_Clause 
                      ORDER_BY_Clause
                     )
FROM [Source]

We are going to use the below-shown data for this demonstration

SQL PERCENT_RANK without Partition By Clause

In this example, we will show what will happen if we omit the Partition By Clause in the PERCENT_RANK Function.

SELECT [FirstName]
      ,[LastName]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
      ,PERCENT_RANK() OVER (ORDER BY [Sales] ASC) AS PercentRank 
  FROM [Employee]

The Order By Clause Sort the Employee table Ascending order using their Sales Amount

ORDER BY [Sales] ASC

Next, the SQL PERCENT_RANK function returns the percentage ranks as the output. Here, a row with the highest sales will assign 1 as the rank, and 0 is the percentile rank for the least sales.

PERCENT_RANK() OVER (ORDER BY [Sales] ASC) AS PercentRank

Let me change the Order by clause from Ascending order to Descending. As you can see, it ranks the least value as 1 and the highest value as 0.

SELECT [FirstName]
      ,[LastName]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
      ,PERCENT_RANK() OVER (ORDER BY [Sales] DESC) AS PercentRank 
  FROM [Employee]

SQL PERCENT_RANK with Partition By Example

How do return the percentage ranks for the partitioned records? The following PERCENT_RANK query will partition the data by Occupation using their Sales amount, and then written the percent ranks for each partition independently.

SELECT [FirstName]
      ,[LastName]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
      ,PERCENT_RANK() OVER (
			     PARTITION BY [Occupation]
			     ORDER BY [Sales] ASC
			    ) AS PercentRank 
  FROM [Employee]

To make sure you understand well. We are changing the SQL Server Group value from Occupation to Education.

SELECT [FirstName]
      ,[LastName]
      ,[Education]
      ,[Occupation]
      ,[YearlyIncome]
      ,[Sales]
      ,PERCENT_RANK() OVER (
			     PARTITION BY [Education]
			     ORDER BY [Sales] ASC
			    ) AS PercentRank 
  FROM [Employee]