How create the required query in sql server

DECLARE @tmp TABLE (Num INT, Alphabet VARCHAR(5))

INSERT INTO @tmp (Num, Alphabet)
VALUES(1, 'A'),
(1, 'B'),
(2, 'C'),
(2, 'D'),
(2, 'E'),
(3, 'F')

SELECT Num, [1] AS Alpha1, [2] AS Alpha2, [3]  AS Alpha3
FROM (
    SELECT *, ROW_NUMBER() OVER(PARTITION BY Num ORDER BY Alphabet) AS Alpha
    FROM @tmp
    ) AS DT
PIVOT (MAX(Alphabet) FOR Alpha IN([1], [2], [3])) AS PT

Num Alpha1  Alpha2  Alpha3
1   A       B       NULL
2   C       D       E
3   F       NULL    NULL