Skip Headers
Oracle® Database SQL Reference
10g Release 2 (10.2)

Part Number B14200-01
Go to Documentation Home
Home
Go to Book List
Book List
Go to Table of Contents
Contents
Go to Index
Index
Go to Master Index
Master Index
Go to Feedback page
Feedback

Go to previous page
Previous
Go to next page
Next
View PDF

COVAR_SAMP

Syntax

Description of covar_samp.gif follows
Description of the illustration covar_samp.gif


See Also:

"Analytic Functions" for information on syntax, semantics, and restrictions

Purpose

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 precedence

Oracle 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.


See Also:

"About SQL Expressions" for information on valid forms of expr and "Aggregate Functions"

Aggregate Example

Please refer to the aggregate example for COVAR_POP.

Analytic Example

Please refer to the analytic example for COVAR_POP.