如何删除同一张表中多行相同的数据但要保留一条？

[夏去秋来]

请问下该如何删除同一张表中有多行相同的数据，但是要保留一行的数据，如下表：


ID name cdefine1 cdefine2 cdefine3
1 aa 101 09-08 15:35
2 aa 101 09-09 15:37
3 bb 101 09-09 15:36
4 cc 204 09-12 14:35
5 cc 204 09-13 12:35
6 dd 255 09-05 15:55
7 ee 255 09-06 18:15
8 ee 211 09-14 11:24


现在我要删除表中字段name和cdefine1相同的数据，就是说只要字段name和cdefine1是一样的就删除，但是要保留一条，最终结果如下：

ID name cdefine1 cdefine2 cdefine3
1 aa 101 09-08 15:35
2 bb 101 09-09 15:36
3 cc 204 09-12 14:35
4 dd 255 09-05 15:55
5 ee 255 09-06 18:15
8 ee 211 09-14 11:24


请问该如何实现？先谢谢啦

[AcHerat]

delete t
from tb t
where exists (select 1 from tb where name=t.name and cdefine1=t.cdefine1 and id>t.id)

[让你望见影子的墙]

select * from tb t
where not exists(select 1 from tb where name=t.name and cdefine1=t.cdefine1 and cdefine3<t.cdefine3)

[--小F--]

delete
 t
from 
 tb t
where 
 exists (select 1 from tb where name=t.name and cdefine1=t.cdefine1 and id>t.id)

[快溜]

delete a from tb a
where exists (select 1 from tb where name=a.name and cdefine1=a.cdefine1 and id>a.id)

[rucypli]

delete a from tb a
where exists (select 1 from tb where name=a.name and cdefine1=a.cdefine1 and id>a.id