Transact-SQL Syntax ConventionsFor SQL Server this function calculates the cumulative distribution of a value within a group of values. In other words, CUME_DIST calculates the relative position of a specified value in a group of values. Assuming ascending ordering, the CUME_DIST of a value in row r is defined as the number of rows with values less than or equal to that value in row r, divided by the number of rows evaluated in the partition or query result set. CUME_DIST is similar to the PERCENT_RANK function.
Transact-SQL Syntax Conventions
OVER ( [ partition_by_clause ] order_by_clause)
The partition_by_clause divides the FROM clause result set into partitions, to which the function is applied. If the partition_by_clause argument is not specified, CUME_DIST treats all query result set rows as a single group. The order_by_clause determines the logical order in which the operation occurs. CUME_DIST requires the order_by_clause. CUME_DIST will not accept the <rows or range clause> of the OVER syntax. See OVER Clause (Transact-SQL) for more information.
float(53)
CUME_DIST returns a range of values greater tnan 0 and less than or equal to 1. Tie values always evaluate to the same cumulative distribution value. CUME_DIST includes NULL values by default and treats these values as the lowest possible values.
CUME_DIST is nondeterministic. See Deterministic and Nondeterministic Functions for more information.
This example uses the CUME_DIST function to calculate the salary percentile for each employee within a given department. CUME_DIST returns a value that represents the percent of employees with a salary less than or equal to the current employee in the same department. The PERCENT_RANK function calculates the percent rank of the employee’s salary within a department. To partition the result set rows by department, the example specifies the partition_by_clause value. The ORDER BY clause of the OVER clause logically orders the rows in each partition. The ORDER BY clause of the SELECT statement determines the display order of the result set.
USE AdventureWorks2012;
GO
SELECT Department, LastName, Rate,
CUME_DIST () OVER (PARTITION BY Department ORDER BY Rate) AS CumeDist,
PERCENT_RANK() OVER (PARTITION BY Department ORDER BY Rate ) AS PctRank
FROM HumanResources.vEmployeeDepartmentHistory AS edh
INNER JOIN HumanResources.EmployeePayHistory AS e
ON e.BusinessEntityID = edh.BusinessEntityID
WHERE Department IN (N'Information Services',N'Document Control')
ORDER BY Department, Rate DESC; Here is the result set.
Department LastName Rate CumeDist PctRank
---------------------- ---------------------- --------------------- ---------------------- ----------------------
Document Control Arifin 17.7885 1 1
Document Control Norred 16.8269 0.8 0.5
Document Control Kharatishvili 16.8269 0.8 0.5
Document Control Chai 10.25 0.4 0
Document Control Berge 10.25 0.4 0
Information Services Trenary 50.4808 1 1
Information Services Conroy 39.6635 0.9 0.888888888888889
Information Services Ajenstat 38.4615 0.8 0.666666666666667
Information Services Wilson 38.4615 0.8 0.666666666666667
Information Services Sharma 32.4519 0.6 0.444444444444444
Information Services Connelly 32.4519 0.6 0.444444444444444
Information Services Berg 27.4038 0.4 0
Information Services Meyyappan 27.4038 0.4 0
Information Services Bacon 27.4038 0.4 0
Information Services Bueno 27.4038 0.4 0
(15 row(s) affected)