SQL SERVER – Introduction to PERCENTILE_CONT() – Analytic Functions Introduced in SQL Server 2012

SQL Server 2012 introduces new analytical function PERCENTILE_CONT().

The book online gives following definition of this function: Calculates a percentile based on a continuous distribution of the column value in Microsoft SQL Server 2012 Release Candidate 0 (RC 0). The result is interpolated and might not be equal to any of the specific values in the column.

If you are clear with understanding of the function – no need to read further. If you got lost here is the same in simple words – it is lot like finding median with percentile value.

Now let’s have fun following query:

USE AdventureWorks
GO
SELECT SalesOrderID, OrderQty, ProductID,
PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY ProductID)
OVER (PARTITION BY SalesOrderID) AS MedianCont
FROM Sales.SalesOrderDetail
WHERE SalesOrderID IN (43670, 43669, 43667, 43663)
ORDER BY SalesOrderID DESC
GO

The above query will give us the following result:

You can see that I have used PERCENTILE_COUNT(0.5) in query, which is similar to finding median. Let me explain above diagram with little more explanation. The defination of median is as following:

In case of Even Number of elements = In ordered list add the two digits from the middle and devide by 2
In case of Odd Numbers of elements = In ordered list select the digits from the middle

I hope this example gives clear idea how PERCENTILE_CONT() works.

Published by Pinal Dave on SQLAuthority. More of my work at pinaldave.com.