Based on what I can make of your post I think you are looking for this:

--sample data

DECLARE @x TABLE (id int not null, value char(1) not null, primary key(id,value));

INSERT INTO @x SELECT 1,'A' UNION ALL SELECT 1,'B' UNION ALL SELECT 2,'A' UNION ALL SELECT 2,'C' UNION ALL

SELECT 2,'B' UNION ALL SELECT 3,'A' UNION ALL SELECT 3,'B' UNION ALL SELECT 3,'C' UNION ALL SELECT 3,'D';

-- common factors

SELECT value FROM (

SELECT value, COUNT(value) AS x

FROM @x

GROUP BY value

HAVING COUNT(value)=(SELECT COUNT(DISTINCT id) FROM @x)) AS x

-- uncommon factors

SELECT value FROM (

SELECT value, COUNT(value) AS xx

FROM @x

GROUP BY value

HAVING COUNT(value)<(SELECT COUNT(DISTINCT id) FROM @x)) AS xx