//查出所有的content唯一的最小id
create table tmp as select min(id) as col1 from test group by content;
//删除重复数据
delete from test where id not in (select col1 from tmp);
//删除临时表
drop table tmp;
参考:http://blog.csdn.net/anya/article/details/6407280
http://zhidao.baidu.com/link?url=UkkbXfHKefCh_kGmoBBGDUO2xIa-gq1ZW-P4rMyP-0RadKMosDSK1SWuyqtGhtdFthc8gY4KwVNaFnvQu_TGEq