delete from Student
  where Name in( select Name from Student group by  Name having count(Name) > 1) and 
 ID not in(select  max(ID) from Student group by  Name having count(Name) > 1 )

Student是要删除的目标表

Name是对应重复的字段

二 大小写敏感

select *
from Student
where Name collate Chinese_PRC_CS_AS != UPPER(Name )

把Name字符串全部改为大写。

collate解释上说其是选择排序用，但也可用在查询区分大小写上，如：
select * from tablename where    column1 collate Chinese_PRC_CS_AS= 'Xxxx'
select * from s where sn collate Chinese_PRC_CS_AS like 'L%'

CI     指定不区分大小写，CS     指定区分大小写。
AI     指定不区分重音，AS     指定区分重音。 
Omitted     指定不区分大小写，WS     指定区分大小写。