符合条件的最小记录

问：

想查找符合qfno='100101' 条件， 且日期whdate为最小的记录，但用下面语句
SELECT * FROM SEAL where qfno='100101' and whdate in (select min(whdate) from seal )
出现日期为库内最小才查得出来，不知道哪里错误，请高手指教。

答：

SELECT a.* FROM SEAL a
where a.qfno='100101' and a.whdate in (select min(whdate) from seal where qfno =a.qfno )

select top 1 * from seal where qfno = '100101' order by whdate asc