REGR_AVGX function [Aggregate]

Function

Computes the average of the independent variable of the regression line.

Syntax 1

REGR_AVGX (dependent-expression, independent-expression)

Syntax 2

REGR_AVGX (dependent-expression, independent-expression)
OVER (window-spec)

window-spec: See Syntax 2 instructions in the Usage section, below.

Parameters

dependent-expression The variable that is affected by the independent variable.

independent-expression The variable that influences the outcome.

Usage

This function converts its arguments to DOUBLE, performs the computation in double-precision floating-point, and returns a DOUBLE as the result. If applied to an empty set, then REGR_AVGX returns NULL.

The function is applied to the set of (dependent-expression and independent-expression) pairs after eliminating all pairs for which either dependent-expression or independent-expression is NULL. The function is computed simultaneously during a single pass through the data. After eliminating NULL values, the following computation is then made, where x represents the independent-expression:

AVG (x)

See "Mathematical formulas for the aggregate functions "in SQL Anywhere Server – SQL Usage.

NoteROLLUP and CUBE are not supported in the GROUP BY clause with Syntax 1. DISTINCT is not supported.

Syntax 2 represents usage as a window function in a SELECT statement. As such, you can specify elements of window-spec either in the function syntax (inline), or with a WINDOW clause in the SELECT statement. For information on how to specify the window, see “Analytical functions”.

Example

The following example calculates the average of the dependent variable, employee age:

SELECT REGR_AVGX( Salary, ( YEAR( NOW() ) - YEAR( BirthDate ) ) )FROM Employees;

Standards and compatibility