查数据: select * from table1 a where rowid !=(select max(rowid) from table1 b where a.name1=b.name1 and a.name2=b.name2......)删数据： delete from table1 a where rowid !=(select max(rowid) from table1 b where a.name1=b.name1 and a.name2=b.name2......)2.group by方法查数据: select count(num), max(name) from student --列出重复的记录数，并列出他的name属性 group by num having count(num) >1 --按num分组后找出表中num列重复，即出现次数大于一次 删数据： delete from student group by num having count(num) >1 这样的话就把所有重复的都删除了。3.用distinct方法 -对于小的表比较有用create table table_new as select distinct * from table1 minux truncate table table1;insert into table1 select * from table_new;
