REGR_AVGX Function [Aggregate]

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)

Parameters

Parameter	Description
dependent-expression	The variable that is affected by the independent variable.
independent-expression	The variable that influences the outcome.

Returns

DOUBLE

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 SQL Anywhere Server - SQL Usage > Querying and Modifying Data > OLAP support > Window functions in SQL Anywhere > Row numbering functions > Mathematical formulas for the aggregate functions.

Note: ROLLUP 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.

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

SQL—ISO/ANSI SQL compliant. SQL/OLAP feature T612.
Sybase—Compatible with SQL Anywhere.