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COVAR_SAMP()

Sample covariance

Result type

DOUBLE PRECISION

Syntax
COVAR_SAMP ( <expr1>, <expr2> )
Table 1. COVAR_SAMP Function Parameters
Parameter Description

exprN

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 COVAR_SAMP returns the sample covariance for a pair of numerical expressions.

The function COVAR_SAMP(<expr1>, <expr2>) is equivalent to

(SUM(<expr1> * <expr2>) - SUM(<expr1>) * SUM(<expr2>) / COUNT(*)) / (COUNT(*) - 1)

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

STDDEV_POP()

Population standard deviation

Result type

DOUBLE PRECISION or NUMERIC depending on the type of expr

Syntax
STDDEV_POP ( <expr> )
Table 1. STDDEV_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 STDDEV_POP returns the population standard deviation for a group or window.NULL values are skipped.

The function STDDEV_POP(<expr>) is equivalent to

SQRT(VAR_POP(<expr>))

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