Oracle® Database SQL Language Reference 11g Release 2 (11.2) Part Number E17118-04 |
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See Also:
"Analytic Functions" for information on syntax, semantics, and restrictionsCOVAR_SAMP
returns the sample covariance of a set of number pairs. You can use it as an aggregate or analytic function.
This function takes as arguments any numeric data type or any nonnumeric data type that can be implicitly converted to a numeric data type. Oracle determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that data type, and returns that data type.
See Also:
Table 3-10, "Implicit Type Conversion Matrix" for more information on implicit conversion and "Numeric Precedence" for information on numeric precedenceOracle Database applies the function to the set of (expr1
, expr2
) pairs after eliminating all pairs for which either expr1
or expr2
is null. Then Oracle makes the following computation:
(SUM(expr1 * expr2) - SUM(expr1) * SUM(expr2) / n) / (n-1)
where n
is the number of (expr1
, expr2
) pairs where neither expr1
nor expr2
is null.
The function returns a value of type NUMBER
. If the function is applied to an empty set, then it returns null.
Refer to the aggregate example for COVAR_POP.
Refer to the analytic example for COVAR_POP.