7.22.7 STDDEV_POP

(1) Specification format

general-set-function-STDDEV_POP ::= STDDEV_POP(value-expression)

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(2) Explanation of specification format

value-expression:

Specifies the input values, in the form of a value expression, that make up the population whose standard deviation is to be determined. For details about value expressions, see 7.20 Value expression.

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(3) Rules

1. Null values are not included in the calculation.

2. In the following cases, the execution result will be a null value.

   • If the number of input rows is 0

   • If the values to be calculated are all null values

3. The execution result of the general set function STDDEV_POP will be equal to the square root of the general set function VAR_POP.

4. The following table shows the data type that can be specified in the value expression and the data type of the execution result of the general set function STDDEV_POP.

   Table 7‒20: Data type that can be specified in the value expression and data type of the execution result of the general set function STDDEV_POP

   No.	Data type that can be specified in the value expression	Data type of the execution result of general set function STDDEV_POP
   1	INTEGER	DOUBLE PRECISION
   2	SMALLINT
   3	DECIMAL(m,n)
   4	DOUBLE PRECISION

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(4) Example

Example

Using the data in the salary table (SALARYLIST), this example determines the standard deviation of a population of employee salaries (SALARY).

SELECT STDDEV_POP("SALARY") AS "STDDEV_POP"
    FROM "SALARYLIST"

Example of execution results

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