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### 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 )```
`window-spec : see Syntax 2 instructions in the Remarks section below`
###### Parameters
• dependent-expression   The variable that is affected by the independent variable.

• independent-expression   The variable that influences the outcome.

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.

###### Standards and compatibility
• SQL/2003   SQL foundation feature (T621) outside core SQL.

###### Example

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

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