CREATE TABLE A_T
(PK CHAR(2)
, AA CHAR(2)
, BB INT)
GO

CREATE TABLE B_T
(PK CHAR(2)
, A1 CHAR(3)
, B1 INT)
GO

INSERT INTO A_T
 SELECT 'AA', '01', 1000 UNION ALL
 SELECT 'AA', '02', 2000 UNION ALL
 SELECT 'BB', '01', 1000 UNION ALL
 SELECT 'CC', '01', 1000 UNION ALL
 SELECT 'CC', '02', 1500
GO

INSERT INTO B_T
 SELECT 'AA',  '001', 800    UNION ALL
 SELECT 'AA',  '002', 1000   UNION ALL
 SELECT 'AA',  '003', 1000   UNION ALL
 SELECT 'BB',  '001', 500   UNION ALL
 SELECT 'BB',  '002', 500   UNION ALL
 SELECT 'CC',  '001', 1000
GO

SELECT
 A.PK
 , A.AA
 , A.BB
 , B.A1
 , B.B1
FROM A_T A
 FULL OUTER JOIN B_T B
 ON  A.PK = B.PK
 AND '0' + A.AA  = B.A1