SQL DATETIME字段比较

比如有个表其中有3个datetime字段，一般来说其中有个datetime字段的值会比其他2个大（修改后日期），那怎么找出这条记录？

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來數據說明吧
...........

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select * from TB where dt1>dt2 and dt1>dt3
union all
select * from TB where dt2>dt1 and dt2>dt3
union all
select * from TB where dt3>dt1 and dt3>dt1

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比较两个日期的差：
用 datediff()

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SQL code:
select * from TB where dt1>dt2 and dt1>dt3
union all
select * from TB where dt2>dt1 and dt2>dt3
union all
select * from TB where dt3>dt1 and dt3>dt1

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找出记录还是找出字段?

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DATEDIFF ( datepart , startdate , enddate )

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SQL code:
create table #test
(dt1 datetime,
dt2 datetime,
dt3 datetime)

insert #test
select '20100110','20091221','20121212' union all
select '20091221','20121212','20100110' union all
select '20121212','20091221','20100110'

select
case when dt1>dt2 and dt1>dt3 then dt1 else null end,
case when dt2>dt1 and dt2>dt3 then dt2 else null end,
case when dt3>dt2 and dt3>dt1 then dt3 else null end
from #test