查找所有重復(fù)標(biāo)題的記錄：
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SELECT * FROM t_info a WHERE ((SELECT COUNT(*) FROM t_info WHERE Title = a.Title) > 1) ORDER BY Title DESC
一、查找重復(fù)記錄
1、查找全部重復(fù)記錄
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Select * From 表 Where 重復(fù)字段 In (Select 重復(fù)字段 From 表 Group By 重復(fù)字段 Having Count(*)>1)
2、過濾重復(fù)記錄(只顯示一條)
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Select * From HZT Where ID In (Select Max(ID) From HZT Group By Title)
注：此處顯示ID最大一條記錄
二、刪除重復(fù)記錄
1、刪除全部重復(fù)記錄(慎用)
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Delete 表 Where 重復(fù)字段 In (Select 重復(fù)字段 From 表 Group By 重復(fù)字段 Having Count(*)>1)
2、保留一條(這個應(yīng)該是大多數(shù)人所需要的 ^_^)
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Delete HZT Where ID Not In (Select Max(ID) From HZT Group By Title)
注：此處保留ID最大一條記錄
三、舉例
1、查找表中多余的重復(fù)記錄，重復(fù)記錄是根據(jù)單個字段(peopleId)來判斷
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select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2、刪除表中多余的重復(fù)記錄，重復(fù)記錄是根據(jù)單個字段(peopleId)來判斷，只留有rowid最小的記錄
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delete from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1)
3、查找表中多余的重復(fù)記錄(多個字段)
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select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、刪除表中多余的重復(fù)記錄(多個字段)，只留有rowid最小的記錄
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delete from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
5、查找表中多余的重復(fù)記錄(多個字段)，不包含rowid最小的記錄
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select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)
四、補(bǔ)充
有兩個以上的重復(fù)記錄，一是完全重復(fù)的記錄，也即所有字段均重復(fù)的記錄，二是部分關(guān)鍵字段重復(fù)的記錄，比如Name字段重復(fù)，而其他字段不一定重復(fù)或都重復(fù)可以忽略。
1、對于第一種重復(fù)，比較容易解決，使用
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select distinct * from tableName
就可以得到無重復(fù)記錄的結(jié)果集。
如果該表需要刪除重復(fù)的記錄(重復(fù)記錄保留1條)，可以按以下方法刪除
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select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp
發(fā)生這種重復(fù)的原因是表設(shè)計不周產(chǎn)生的，增加唯一索引列即可解決。
2、這類重復(fù)問題通常要求保留重復(fù)記錄中的第一條記錄，操作方法如下
假設(shè)有重復(fù)的字段為Name,Address，要求得到這兩個字段唯一的結(jié)果集
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select identity(int,1,1) as autoID, * into #Tmp from tableName
select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID
select * from #Tmp where autoID in(select autoID from #tmp2)