PERCENTILE_DISC (Transact-SQL)

**APPLIES TO:** ![yes](media/yes.png)SQL Server (starting with 2012) ![yes](media/yes.png)Azure SQL Database ![yes](media/yes.png)Azure SQL Data Warehouse ![yes](media/yes.png)Parallel Data Warehouse

Computes a specific percentile for sorted values in an entire rowset or within distinct partitions of a rowset in SQL Server For a given percentile value P, PERCENTILE_DISC sorts the values of the expression in the ORDER BY clause and returns the value with the smallest CUME_DIST value (with respect to the same sort specification) that is greater than or equal to P. For example, PERCENTILE_DISC (0.5) will compute the 50th percentile (that is, the median) of an expression. PERCENTILE_DISC calculates the percentile based on a discrete distribution of the column values; the result is equal to a specific value in the column.

Topic link icon Transact-SQL Syntax Conventions (Transact-SQL)

Syntax

PERCENTILE_DISC ( numeric_literal ) WITHIN GROUP ( ORDER BY order_by_expression [ ASC | DESC ] )  
    OVER ( [ <partition_by_clause> ] )

Arguments

literal
The percentile to compute. The value must range between 0.0 and 1.0.

WITHIN GROUP ( ORDER BY order_by_expression [ ASC | DESC ])
Specifies a list of values to sort and compute the percentile over. Only one order_by_expression is allowed. The default sort order is ascending. The list of values can be of any of the data types that are valid for the sort operation.

OVER ( <partition_by_clause> )
Divides the result set produced by the FROM clause into partitions to which the percentile function is applied. For more information, see OVER Clause (Transact-SQL). The <ORDER BY clause> and <rows or range clause>cannot be specified in a PERCENTILE_DISC function.

Return Types

The return type is determined by the order_by_expression type.

Compatibility Support

Under compatibility level 110 and higher, WITHIN GROUP is a reserved keyword. For more information, see ALTER DATABASE Compatibility Level (Transact-SQL).

General Remarks

Any nulls in the data set are ignored.

PERCENTILE_DISC is nondeterministic. For more information, see Deterministic and Nondeterministic Functions.

Examples

A. Basic syntax example

The following example uses PERCENTILE_CONT and PERCENTILE_DISC to find the median employee salary in each department. Note that these functions may not return the same value. This is because PERCENTILE_CONT interpolates the appropriate value, whether or not it exists in the data set, while PERCENTILE_DISC always returns an actual value from the set.

USE AdventureWorks2012;  
  
SELECT DISTINCT Name AS DepartmentName  
      ,PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY ph.Rate)   
                            OVER (PARTITION BY Name) AS MedianCont  
      ,PERCENTILE_DISC(0.5) WITHIN GROUP (ORDER BY ph.Rate)   
                            OVER (PARTITION BY Name) AS MedianDisc  
FROM HumanResources.Department AS d  
INNER JOIN HumanResources.EmployeeDepartmentHistory AS dh   
    ON dh.DepartmentID = d.DepartmentID  
INNER JOIN HumanResources.EmployeePayHistory AS ph  
    ON ph.BusinessEntityID = dh.BusinessEntityID  
WHERE dh.EndDate IS NULL;

Here is a partial result set.

DepartmentName        MedianCont    MedianDisc
--------------------   ----------   ----------
Document Control       16.8269      16.8269
Engineering            34.375       32.6923
Executive              54.32695     48.5577
Human Resources        17.427850    16.5865

Examples: [!INCLUDEssSDWfull] and [!INCLUDEssPDW]

B. Basic syntax example

-- Uses AdventureWorks  
  
SELECT DISTINCT DepartmentName  
       ,PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY BaseRate)  
        OVER (PARTITION BY DepartmentName) AS MedianCont  
       ,PERCENTILE_DISC(0.5) WITHIN GROUP (ORDER BY BaseRate)  
        OVER (PARTITION BY DepartmentName) AS MedianDisc  
FROM dbo.DimEmployee;