假设有满足如下条件的表记录，
SELECT A.flags FROM A, B
WHERE A.id = B.id AND A.flags = '1' AND B.list01 IS NOT NULL
AND NOT EXISTS(SELECT 1 FROM C WHERE C.attID=2090 AND C.parentid=A.id);
此时A.flags值为1，如果想把A.flags的值update为0，update语句应该怎么写呢？
请指教!
------解决方案--------------------
UPDATE A SET FLAG=0
WHERE
EXISTS(SELECT 1 FROM B WHERE A.id = B.id AND A.flags = '1' AND B.list01 IS NOT NULL)
AND NOT EXISTS(SELECT 1 FROM C WHERE C.attID=2090 AND C.parentid=A.id)
AND FLAG=1;