SQL - UNIR REGISTROS

CREATE TABLE #Test(KEYPRS CHAR(3), KEYTND CHAR(3), KEYCAT CHAR(3))

INSERT INTO #Test VALUES('127','238', NULL),

('127',NULL, '7')

SELECT * FROM #Test

SELECT T1.KEYPRS, T1.KEYTND,

CASE WHEN T1.KEYCAT IS NULL THEN T2.KEYCAT ELSE T1.KEYCAT END KEYCAT

FROM #Test T1 INNER JOIN (SELECT KEYPRS, KEYTND, KEYCAT FROM #Test WHERE KEYCAT IS NOT NULL)  T2

ON T1.KEYPRS = T2.KEYPRS

WHERE T1.KEYTND IS NOT NULL