DECLARE @T TABLE
    (Customer VARCHAR(5), sn INT, val1 INT, val2 INT, Val3 INT)

INSERT INTO @T
SELECT 'A', 1, 31, 54, NULL
UNION ALL SELECT 'A', 2, 98, 21, 65
UNION ALL SELECT 'A', 3, 44, 67, 11

;WITH MyVals AS (
    SELECT Customer, sn, n=1, val=val1
    FROM @T
    UNION ALL
    SELECT Customer, sn, 2, val2
    FROM @T
    UNION ALL
    SELECT Customer, sn, 3, val3
    FROM @T
    )
SELECT Customer
    ,val1_1=MAX(CASE WHEN sn=1 AND n=1 THEN val END) 
    ,val1_2=MAX(CASE WHEN sn=1 AND n=2 THEN val END) 
    ,val1_3=MAX(CASE WHEN sn=1 AND n=3 THEN val END) 
    ,val2_1=MAX(CASE WHEN sn=2 AND n=1 THEN val END) 
    ,val2_2=MAX(CASE WHEN sn=2 AND n=2 THEN val END) 
    ,val2_2=MAX(CASE WHEN sn=2 AND n=3 THEN val END) 
    ,val3_1=MAX(CASE WHEN sn=3 AND n=1 THEN val END) 
    ,val3_2=MAX(CASE WHEN sn=3 AND n=2 THEN val END) 
    ,val3_3=MAX(CASE WHEN sn=3 AND n=3 THEN val END) 
FROM MyVals
WHERE val IS NOT NULL
GROUP BY Customer