7.22.7 STDDEV_POP
STDDEV_POP determines the standard deviation of a population.
- Organization of this subsection
(1) Specification format
general-set-function-STDDEV_POP ::= STDDEV_POP(value-expression)
(2) Explanation of specification format
- value-expression:
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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.
(3) Rules
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Null values are not included in the calculation.
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In the following cases, the execution result will be a null value.
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If the number of input rows is 0
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If the values to be calculated are all null values
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The execution result of the general set function STDDEV_POP will be equal to the square root of the general set function VAR_POP.
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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
(4) Example
- Example
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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