这条SQL语句该怎么写？

[tinwoo]

表A：有字段sercode varchar2(10)
表B：有字段sercode varchar2(10)，sendtime date
表C：有字段sercode varchar2(10), sendtime date

请问，我现想从表B中找出 B.sercode = A.sercode and B.sendtime =sysdate 的记录插入表C中，
由于这条SQL是循环执行，怎么样才能保证已插入表C中的记录不再重复插入？？？？
望高手指点，谢先！！！

[dinya2003]

写用过程,用游标来处理..

[wylwyl1130]

不知道你是想说“你想循环执行这条语句“还是“这条sql语句是循环执行的“
如果是第一种，也就说表B是增加的，可以考虑触发器来执行
如果是第二中，直接
insert into C
select * from B where B.sercode = A.sercode and B.sendtime =sysdate
即可

[sijian2001]

INSERT INTO C (SERCODE, SENDTIME)
SELECT DISTINCT B.SERCODE, B.SENDTIME
FROM A, B
WHERE B.SERCODE = A.SERCODE
AND B.SENDTIME = SYSDATE
AND NOT EXISTS (SELECT * FROM C WHERE B.SERCODE = C.SERCODE AND B.SENDTIME = C.SENDTIME)

[yogihoo]

insert into C
select * from B where B.sercode = A.sercode and B.sendtime =sysdate and
B.sercode not in (select sercode from C)

[daihaidong]

insert into c(sercode , sendtime )
(select sercode, sendtime from a, b
where B.sercode = A.sercode and B.sendtime =sysdate
and (( B.sercode, B.sendtime ) NOT IN (SELECT C.sercode, C.sendtime FROM C)))