(一)

1、查詢表中重復(fù)數(shù)據(jù)。select * from people

where peopleId in (select?? peopleId?? from?? people?? group?? by?? peopleId?? having?? count(peopleId) > 1)

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2、刪除表中多余的重復(fù)記錄，重復(fù)記錄是根據(jù)單個(gè)字段（peopleId）來判斷，只留有rowid最小的記錄

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)

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3、查找表中多余的重復(fù)記錄（多個(gè)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)

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4、刪除表中多余的重復(fù)記錄（多個(gè)字段），只留有rowid最小的記錄

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)

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5、查找表中多余的重復(fù)記錄（多個(gè)字段），不包含rowid最小的記錄

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)

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(二)

比方說

在A表中存在一個(gè)字段“name”，

而且不同記錄之間的“name”值有可能會(huì)相同，

現(xiàn)在就是需要查詢出在該表中的各記錄之間，“name”值存在重復(fù)的項(xiàng)；

Select Name,Count(*) From A Group By Name Having Count(*) > 1

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如果還查性別也相同大則如下:

Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1

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(三)

方法一

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declare @max integer,@id integer

declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >； 1

open cur_rows

fetch cur_rows into @id,@max

while @@fetch_status=0

begin

select @max = @max -1

set rowcount @max

delete from 表名 where 主字段 = @id

fetch cur_rows into @id,@max

end

close cur_rows

set rowcount 0

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方法二

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＂重復(fù)記錄＂有兩個(gè)意義上的重復(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(duì)于第一種重復(fù)，比較容易解決，使用

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?jiǎng)h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

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(jì)不周產(chǎn)生的，增加唯一索引列即可解決。

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　　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(gè)字段唯一的結(jié)果集

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)

　　最后一個(gè)select即得到了Name，Address不重復(fù)的結(jié)果集（但多了一個(gè)autoID字段，實(shí)際寫時(shí)可以寫在select子句中省去此列）

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(四)

查詢重復(fù)

select * from tablename where id in (select id from tablename group by id

having count(id) > 1）

查詢和刪除表中重復(fù)數(shù)據(jù)sql語句