STDDEV [aggregate]

Evaluates the statistical sample standard deviation for each member of the group.

Evaluates the statistical sample standard deviation for each member of the group. The return value is the same as the square root of VAR_SAMP:

STDDEV(expression) = SQRT(VAR_SAMP(expression))

Behavior type

Immutable

Syntax

STDDEV ( expression )

Parameters

expression
Any NUMERIC data type or any non-numeric data type that can be implicitly converted to a numeric data type. STDDEV returns the same data type as expression.

  • Nonstandard function STDDEV is provided for compatibility with other databases. It is semantically identical to STDDEV_SAMP.

  • This aggregate function differs from analytic function STDDEV, which computes the statistical sample standard deviation of the current row with respect to the group of rows within a window.

  • When VAR_SAMP returns NULL, STDDEV returns NULL.

Examples

The following example returns the statistical sample standard deviation for each household ID from the customer_dimension table of the VMart example database:

=> SELECT STDDEV(household_id) FROM customer_dimension;
   STDDEV
-----------------
 8651.5084240071