--过滤掉重复记录，只保留一条数据
delete from
gzfw_yhxx
where Zjhm in (select Zjhm from gzfw_yhxx group by Zjhm
having count(Zjhm) > 1)
and rowid not in (select min(rowid) from
gzfw_yhxx group by Zjhm having count(Zjhm
)>1)
原文：http://www.cnblogs.com/lanjianqing/p/5408996.html