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STDDEV_SAMP Examples

select
  dept_no
  stddev_samp(salary)
from employee
group by dept_no

VAR_POP()

Population variance

Result type

DOUBLE PRECISION or NUMERIC depending on the type of expr

Syntax
VAR_POP ( <expr> )
Table 1. VAR_POP Function Parameters
Parameter Description

expr

Numeric expression.It may contain a table column, a constant, a variable, an expression, a non-aggregate function or a UDF.Aggregate functions are not allowed as expressions.

The function VAR_POP returns the population variance for a group or window.NULL values are skipped.

The function VAR_POP(<expr>) is equivalent to

(SUM(<expr> * <expr>) - SUM (<expr>) * SUM (<expr>) / COUNT(<expr>))
  / COUNT (<expr>)

If the group or window is empty, or contains only NULL values, the result will be NULL.

VAR_SAMP()

Sample variance

Result type

DOUBLE PRECISION or NUMERIC depending on the type of expr

Syntax
VAR_SAMP ( <expr> )
Table 1. VAR_SAMP Function Parameters
Parameter Description

expr

Numeric expression.It may contain a table column, a constant, a variable, an expression, a non-aggregate function or a UDF.Aggregate functions are not allowed as expressions.

The function VAR_POP returns the sample variance for a group or window.NULL values are skipped.

The function VAR_SAMP(<expr>) is equivalent to

(SUM(<expr> * <expr>) - SUM(<expr>) * SUM (<expr>) / COUNT (<expr>))
  / (COUNT(<expr>) - 1)

If the group or window is empty, contains only 1 row, or contains only NULL values, the result will be NULL.