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PERCENTILE_DISC (Transact-SQL)

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW) SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

Computes a specific percentile for sorted values in an entire rowset or within a rowset's distinct partitions in SQL Server. For a given percentile value P, PERCENTILE_DISC sorts the expression values in the ORDER BY clause. It then returns the value with the smallest CUME_DIST value given (with respect to the same sort specification) that's greater than or equal to P. For example, PERCENTILE_DISC (0.5) computes 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 column value.

Transact-SQL syntax conventions

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 FROM clause's result set into partitions. The percentile function is applied to these partitions. For more information, see SELECT - OVER clause. The <ORDER BY clause> and <rows or range clause>can't 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.

Remarks

Any nulls in the data set are ignored.

PERCENTILE_DISC is nondeterministic. For more information, see Deterministic and nondeterministic functions.

Examples

Basic syntax example

The following example uses PERCENTILE_CONT and PERCENTILE_DISC to find each department's median employee salary. They might not return the same value:

  • PERCENTILE_CONT returns the appropriate value, even if it doesn't exist in the data set.
  • PERCENTILE_DISC returns an actual set value.
USE AdventureWorks2022;
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's 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: Azure Synapse Analytics and Analytics Platform System (PDW)

Basic syntax example

The following example uses PERCENTILE_CONT and PERCENTILE_DISC to find each department's median employee salary. They might not return the same value:

  • PERCENTILE_CONT returns the appropriate value, even if it doesn't exist in the data set.
  • PERCENTILE_DISC returns an actual set value.
-- 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;

Here's a partial result set.

DepartmentName        MedianCont    MedianDisc
--------------------   ----------   ----------
Document Control       16.826900    16.8269
Engineering            34.375000    32.6923
Human Resources        17.427850    16.5865
Shipping and Receiving  9.250000     9.0000

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