IF OBJECT_ID('dbo.gcd') IS NOT NULL DROP FUNCTION dbo.gcd
GO

CREATE FUNCTION dbo.gcd (@a INT, @b INT) RETURNS INT AS BEGIN
	IF @b = 0 RETURN @a
	ELSE RETURN dbo.gcd(@b, @a % @b)
	RETURN -1
END
GO

IF OBJECT_ID('dbo.lcm') IS NOT NULL DROP FUNCTION dbo.lcm
GO

CREATE FUNCTION lcm(@a INT, @b INT) RETURNS INT AS BEGIN
	RETURN (@a * @b) / dbo.gcd(@a, @b)
END
GO

CREATE FUNCTION dbo.fnGCD
(
	@a INT,
	@b INT
)
RETURNS INT
AS
BEGIN
	DECLARE	@c INT

	IF @a IS NULL OR @b IS NULL OR (@a = 0 AND @b = 0)
		RETURN NULL

	IF @a = 0 OR @b = 0
		RETURN ABS(@a) + ABS(@b)

	IF ABS(@a) < ABS(@b)
		SELECT	@c = ABS(@a),
			@a = ABS(@b),
			@b = @c
	ELSE
		SELECT	@a = ABS(@a),
			@b = ABS(@b)

	SET	@c = @a % @b

	WHILE @c > 0
		SELECT	@a = @b,
			@b = @c,
			@c = @a % @b

	RETURN	@b
END