VARP (Transact-SQL)

VARP (Transact-SQL)

 

THIS TOPIC APPLIES TO:yesSQL Server (starting with 2008) yesAzure SQL Database yesAzure SQL Data Warehouse yesParallel Data Warehouse

Returns the statistical variance for the population for all values in the specified expression.

Topic link icon Transact-SQL Syntax Conventions


VARP ( [ ALL | DISTINCT ] expression )
   OVER ( [ partition_by_clause ] order_by_clause )  nh
-- Azure SQL Data Warehouse and Parallel Data Warehouse
      -- Aggregate Function Syntax 
VARP ( [ ALL | DISTINCT ] expression )
-- Azure SQL Data Warehouse and Parallel Data Warehouse
      -- Analytic Function Syntax
VARP (expression) OVER ( [ partition_by_clause ] order_by_clause)

ALL

Applies the function to all values. ALL is the default.

DISTINCT

Specifies that each unique value is considered.

expression

Is an expression of the exact numeric or approximate numeric data type category, except for the bit data type. Aggregate functions and subqueries are not permitted.

OVER ( [ partition_by_clause ] order_by_clause )

partition_by_clause divides the result set produced by the FROM clause into partitions to which the function is applied. If not specified, the function treats all rows of the query result set as a single group. order_by_clause determines the logical order in which the operation is performed. order_by_clause is required. For more information, see OVER Clause (Transact-SQL).

If VARP is used on all items in a SELECT statement, each value in the result set is included in the calculation. VARP can be used with numeric columns only. Null values are ignored.

VARP is a deterministic function when used without the OVER and ORDER BY clauses. It is nondeterministic when specified with the OVER and ORDER BY clauses. For more information, see Deterministic and Nondeterministic Functions.

The following example returns the variance for the population for all bonus values in the SalesPerson table in the AdventureWorks2012 database.

SELECT VARP(Bonus)
FROM Sales.SalesPerson;
GO

The following example returns the VARPof the sales quota values in the table dbo.FactSalesQuota. The first column contains the variance of all distinct values and the second column contains the variance of all values including any duplicates values.

-- Uses AdventureWorks

SELECT VARP(DISTINCT SalesAmountQuota)AS Distinct_Values, VARP(SalesAmountQuota) AS All_Values
FROM dbo.FactSalesQuota;

Here is the result set.

Distinct_Values   All_Values

----------------  ----------------

158146830494.18   157788848582.94

The following example returns the VARP of the sales quota values for each quarter in a calendar year. Notice that the ORDER BY in the OVER clause orders the statistical variance and the ORDER BY of the SELECT statement orders the result set.

-- Uses AdventureWorks

SELECT CalendarYear AS Year, CalendarQuarter AS Quarter, SalesAmountQuota AS SalesQuota,
       VARP(SalesAmountQuota) OVER (ORDER BY CalendarYear, CalendarQuarter) AS Variance
FROM dbo.FactSalesQuota
WHERE EmployeeKey = 272 AND CalendarYear = 2002
ORDER BY CalendarQuarter;

Here is the result set.

Year  Quarter  SalesQuota              Variance

----  -------  ----------------------  -------------------

2002  1         91000.0000             0.00

2002  2        140000.0000             600250000.00

2002  3         70000.0000             860222222.22

2002  4        154000.0000             1185187500.00

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