something like this??

DECLARE @Input TABLE

(

col1 INT,

col2 INT,

col3 VARCHAR(3),

col4 VARCHAR(3),

col5 VARCHAR(3)

)

INSERT INTO @Input VALUES(1, 122, 'AAA', null, null),(2, 122, null, 'BBB', null),(3, 122, null, null, 'CCC'),

(4, 156, null, 'BBB', null), (5, 156, 'AAA', null, null), (6, 156, null, null, 'CCC')

SELECT col2, MAX(col3) as col3, MAX(col4) as col4, MAX(col5) as col5

FROM @Input

GROUP BY col2