SQL删除重复记录保留一条的问题

今天，有个网友来请教小编sql删除重复记录的问题，他的数据库中有大量的重复记录，他只想保留一条，这个问题可把小编难住了，因为小编对sql SERVER不太熟悉，在网上搜了一下，代码如下：

table sturcture

{taskRecordId,taskDate,userId,teamId,taskId,unit,nots}

delete duplicate taskDate,UserId,teamId and taskId.

the sql is

delete from TaskRecord
select * from TaskRecord
where taskRecordId in
(
select MIN(taskRecordId) from TaskRecord t join
(select COUNT(*) d,teamId from TaskRecord
where taskId=6
group by taskDate,teamId having (COUNT(*)>1)) x
on t.taskDate=x.taskDate and t.userId=x.userId and t.teamId
=x.teamId where t.taskId=6 group by t.taskDate,t.userId,t.teamId
)