問題:
table
id field1 field2
1 1 qq
2 1 qq
3 2 aa
4 2 aa
如何將重複的行刪除掉,結果爲
table
id field1 field2
1 1 qq
3 2 aa
解決辦法:
1.如果有id
delete from tablename a where exists(select * from tablename where a.id<id and a.col1=col1)
2.如果沒有id
alter table tablename add id int identity(1,1)
delete from tablename a where exists(select * from tablename where a.id<id and a.col1=col1)
alter table drop cloumn id