1、查找表中多餘的重複記錄,重複記錄是根據單個字段(peopleId)來判斷 select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2、刪除表中多餘的重複記錄,重複記錄是根據單個字段(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)
3、查找表中多餘的重複記錄(多個字段) select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、刪除表中多餘的重複記錄(多個字段),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)
5、查找表中多餘的重複記錄(多個字段),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)
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, 現在就是需要查詢出在該表中的各記錄之間,“name”值存在重複的項; 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 ------------------------------------------------------------------------------------------------ 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
方法二 有兩個意義上的重複記錄,一是完全重複的記錄,也即所有字段均重複的記錄,二是部分關鍵字段重複的記錄,比如Name字段重複,而其他字段不一定重複或都重複可以忽略。 1、對於第一種重複,比較容易解決,使用 select distinct * from tableName 就可以得到無重複記錄的結果集。 如果該表需要刪除重複的記錄(重複記錄保留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 發生這種重複的原因是表設計不周產生的,增加唯一索引列即可解決。
2、這類重複問題通常要求保留重複記錄中的第一條記錄,操作方法如下 假設有重複的字段爲Name,Address,要求得到這兩個字段唯一的結果集 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) 最後一個select即得到了Name,Address不重複的結果集(但多了一個autoID字段,實際寫時可以寫在select子句中省去此列) select * from tablename where id in ( select id from tablename group by id having count(id) > 1)
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