DECLARE @x1 FLOAT
DECLARE @x2 FLOAT
DECLARE @y1 FLOAT
DECLARE @y2 FLOAT

SELECT @x1 = 1, @x2 = 2, @y1 = 1, @y2 = 2
SELECT (@y2-@y1)/(@x2-@x1)
                                                      
----------------------------------------------------- 
1.0

(1 row(s) affected)

Oder als UDF

CREATE FUNCTION dbo.steigung(@y1 FLOAT,@y2 FLOAT, @x1 FLOAT, @x2 FLOAT)
RETURNS FLOAT
	AS
		BEGIN
			RETURN (@y2-@y1)/(@x2-@x1)
	END
GO

SELECT dbo.steigung(1,2,1,2)
DROP FUNCTION dbo.steigung

                                                      
----------------------------------------------------- 
1.0

(1 row(s) affected)