Вот что вам нужно сделать как SQL Fiddle .
И для справки:
CREATE TABLE TestData
([ID] varchar(1),
[date] int,
[rownum] int,
[subid] varchar(1),
[value1] int,
[value2] int)
;
INSERT INTO TestData
([ID], [date], [rownum], [subid], [value1], [value2])
VALUES
('A', 200911, 1, 'X', 10, 20),
('A', 200911, 2, 'Y', 15, 25),
('B', 201001, 2, 'S', 60, 35),
('B', 201001, 1, 'R', 40, 50)
;
SELECT A.ID, A.date, A.rownum, A.subid, A.value1, A.value2, B.value1 AS r2value1, B.value2 AS r2value2
FROM TestData AS A
INNER JOIN TestData B ON A.id = B.id AND B.rownum = 2
WHERE A.rownum = 1