查找數(shù)據(jù)庫中重復(fù)及數(shù)據(jù)【經(jīng)典】-資料下載頁
2025-08-23 16:00本頁面
【正文】 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select * from peoplewhere peopleId in (select peopleId from people group by peopleId having count(peopleId) 1)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delete from peoplewhere 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)查找表中多余的重復(fù)記錄（多個字段）select * from vitae awhere (,) in (select peopleId,seq from vitae group by peopleId,seq having count(*) 1)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delete from vitae awhere (,) 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)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select * from vitae awhere (,) 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)(二)比方說在A表中存在一個字段“name”，而且不同記錄之間的“name”值有可能會相同，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；Select Name,Count(*) From A Group By Name Having Count(*) 1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(三)方法一declare @max integer,@id integerdeclare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) ； 1open cur_rowsfetch cur_rows into @id,@maxwhile @@fetch_status=0beginselect @max = @max 1set rowcount @maxdelete from 表名 where 主字段 = @idfetch cur_rows into @id,@maxendclose cur_rowsset rowcount 0 方法二 有兩個意義上的重復(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?！ τ诘谝环N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select distinct * into Tmp from tableNamedrop table tableNameselect * into tableName from Tmpdrop 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?！ ∵@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select identity(int,1,1) as autoID, * into Tmp from tableNameselect min(autoID) as autoID into Tmp2 from Tmp group by Name,autoIDselect * from Tmp where autoID in(select autoID from tmp2) 最后一個select即得到了Name，Address不重復(fù)的結(jié)果集（但多了一個autoID字段，實際寫時可以寫在select子句中省去此列）(四)查詢重復(fù)select * from tablename where id in (select id from tablenamegroup by idhaving count(id) 1)
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