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Computes the slope of the linear regression line, fitted to non-NULL pairs.
REGR_SLOPE(dependent-expression, independent-expression)
REGR_SLOPE(dependent-expression, independent-expression)
OVER (window-spec)
window-spec: See Syntax 2 instructions in the Usage section below.
dependent-expression The variable that is affected by the independent variable.
independent-expression The variable that influences the outcome.
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_SLOPE returns NULL.
REGR_SLOPE 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 made, where y represents the dependent-expression and x represents the independent-expression:
COVAR_POP(x, y) / VAR_POP(y)
See "Mathematical formulas for the aggregate functions "in SQL Anywhere Server – SQL Usage.
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. For information on how to specify the window, see “Analytical functions”.
The following example returns the value 935.3429749445614:
SELECT REGR_SLOPE( Salary, ( YEAR( NOW() ) - YEAR( BirthDate ) ) )FROM Employees;
