/*求两个数的最大公约数*/

CREATE  FUNCTION f_GetGys

    (

      @num1 BIGINT ,

      @num2 BIGINT

    )

RETURNS BIGINT

AS

    BEGIN

        DECLARE @m BIGINT;

        DECLARE @i BIGINT;

        IF ( @num1 < @num2 )--确保@num1永远是大的 @num2永远是小的

            BEGIN

                SET @m = @num2;

                SET @num2 = @num1;

                SET @num1 = @m;

            END;

        SET @i = @num1 % @num2;

        WHILE @i > 0

            BEGIN

                SELECT  @num1 = @num2 ,

                        @num2 = @i ,

                        @i = @num1 % @num2;

            END;

        RETURN @num2;

    END;

GO

/*求两个数的最小公倍数（调用了最大公约数函数，也可以直接写进去）*/

CREATE  FUNCTION f_GetGbs

    (

      @num1 BIGINT ,

      @num2 BIGINT

    )

RETURNS BIGINT

AS

    BEGIN

        DECLARE @a BIGINT;

        DECLARE @b BIGINT;

        DECLARE @c BIGINT;

        DECLARE @d BIGINT;

        SET @a = @num1;

        SET @b = @num2;

        SET @c = dbo.f_GetGys(@num1, @num2);

        SET @d = @a * @b / @c;

        RETURN @d;

    END;

GO

摘自：http://bbs.csdn.net/topics/380047119