sql 求两张表中同一字段数值相加

INSERT INTO A (A.A1) SELECT B.A1FROM BWHERE B.A1 NOT IN (SELECT A.A1 FROM A);UPDATE A,(SELECT C.A1, SUM(C.A2) AS A2 FROM ( SELECT * FROM A UNION ALL SELECT * FROM B ) C GROUP BY A1)D SET A.A2 = D.A2 WHERE A.A1 = D.A1