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STDEV (Transact-SQL)

Returns the statistical standard deviation of all values in the specified expression.

Applies to: SQL Server (SQL Server 2008 through current version), Azure SQL Database.

Topic link icon Transact-SQL Syntax Conventions

STDEV ( [ ALL | DISTINCT ] expression ) 
   OVER ( [ partition_by_clause ] order_by_clause )  


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


Specifies that each unique value is considered.


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

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

STDEV 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 standard deviation for all bonus values in the SalesPerson table in the AdventureWorks2012 database.

FROM Sales.SalesPerson;

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