SQL對(duì)冗余數(shù)據(jù)的刪除重復(fù)記錄只保留單條的說明

public SeqListint> Purge(SeqListint> La)
{
SeqListint> Lb = new SeqListint>(La.Maxsize);
//將a表中的第1個(gè)數(shù)據(jù)元素賦給b表
Lb.Append(La[0]);
//依次處理a表中的數(shù)據(jù)元素
for (int i = 1; i = La.GetLength() - 1; ++i)
{
int j = 0;
//查看b表中有無與a表中相同的數(shù)據(jù)元素
for (j = 0; j = Lb.GetLength() - 1; ++j)
{
//有相同的數(shù)據(jù)元素
if (La[i].CompareTo(Lb[j]) == 0)
{
break;
}
}
//沒有相同的數(shù)據(jù)元素，將a表中的數(shù)據(jù)元素附加到b表的末尾。
if (j > Lb.GetLength() - 1)
{
Lb.Append(La[i]);
}
return Lb;
}
}

select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp

select * from test;select * from test group by id having count(*)>1select * from test group by idselect distinct * from testdelete from test a where a.rowid!=(select max(rowid) from test b where a.id=b.id);扯遠(yuǎn)了，回到原來的問題，除了采用數(shù)據(jù)結(jié)構(gòu)的思想來處理，因?yàn)閿?shù)據(jù)庫特有的事務(wù)處理，能夠把數(shù)據(jù)緩存在線程池里，這樣也相當(dāng)于臨時(shí)表的功能，所以，我們還可以用游標(biāo)來解決刪除重復(fù)記錄的問題。
declare @max int,
@id int
declare cur_rows cursor local for select id ,count(*) from test group by id having count(*) > 1
open cur_rows
fetch cur_rows into @id ,@max
while @@fetch_status=0
begin
select @max = @max -1
set rowcount @max --讓這個(gè)時(shí)候的行數(shù)等于少了一行的統(tǒng)計(jì)數(shù),想想看,為什么
delete from test where id = @id
fetch cur_rows into @id ,@max
end
close cur_rows
set rowcount 0 以上是閃電查閱一些資料寫出的想法，有考慮不周的地方，歡迎大家指出。