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 Remarks section below

Parameters

Returns

DOUBLE

Remarks

This function converts its arguments to DOUBLE, and performs the computation in double-precision floating point. If the function is applied to an empty set, then it 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 )

For more information about the statistical computation performed, see Mathematical formulas for the aggregate functions.

Syntax 2 represents usage as a window function in a SELECT statement. As such, elements of window-spec can be specified either in the function syntax (inline), or in conjunction with a WINDOW clause in the SELECT statement. See the window-spec definition provided in WINDOW clause.

For more information about using window functions in SELECT statements, including working examples, see Window functions.

See also

• AVG function [Aggregate]
• REGR_COUNT function [Aggregate]
• REGR_INTERCEPT function [Aggregate]
• REGR_COUNT function [Aggregate]
• REGR_SLOPE function [Aggregate]
• REGR_SXX function [Aggregate]
• REGR_SXY function [Aggregate]
• REGR_SYY function [Aggregate]
• REGR_AVGY function [Aggregate]

Standards and compatibility

Example

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

SELECT REGR_AVGX( Salary, ( 2008 - YEAR( BirthDate ) ) )
FROM Employees;