| Oracle® Database SQL Language Reference 11g Release 1 (11.1) Part Number B28286-01 |
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View PDF |
| Oracle® Database SQL Language Reference 11g Release 1 (11.1) Part Number B28286-01 |
|
|
View PDF |
Syntax
See Also:
"Analytic Functions" for information on syntax, semantics, and restrictionsPurpose
COVAR_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 datatype or any nonnumeric datatype that can be implicitly converted to a numeric datatype. Oracle determines the argument with the highest numeric precedence, implicitly converts the remaining arguments to that datatype, and returns that datatype.
See Also:
Table 2-10, "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.
Aggregate Example
Refer to the aggregate example for COVAR_POP.
Analytic Example
Refer to the analytic example for COVAR_POP.
