完全重復(fù)數(shù)據(jù)，可能導(dǎo)致錄入等等錯(cuò)誤...
查詢無重復(fù)結(jié)果：
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 kc_wzmx
delete from kc_wzmx
insert into kc_wzmx select * from #tmp
kc_wzmx為表名，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。
查詢，列出htfphm_、gg_和kbh_三個(gè)字段完全重復(fù)的數(shù)據(jù)；
select * from kc_wzmx aa
where (select Count(1) from kc_wzmx where aa.htfphm_=htfphm_ and aa.gg_=gg_ and aa.kbh_=kbh_ )>1
SQL Server刪除表及刪除表中數(shù)據(jù)的方法
刪除表的T-SQL語句為：
drop table <表名>
drop是丟棄的意思，drop table表示將一個(gè)表徹底刪除掉。
刪除表數(shù)據(jù)有兩種方法：delete和truncate。
delete的用法如下：
delete from <表名> [where條件]
truncate的用法如下：
truncate table <表名>
delete和truncate的區(qū)別如下：
1、delete可以刪除表中的一條或多條數(shù)據(jù)，也可以刪除全部數(shù)據(jù)；而truncate只能將表中的全部數(shù)據(jù)刪除。
2、delete刪除表數(shù)據(jù)后，標(biāo)識(shí)字段不能復(fù)用。也就是說如果你把id=10（假如id是標(biāo)識(shí)字段）的那行數(shù)據(jù)刪除了，你也不可能再插入一條數(shù)據(jù)讓id=10.
3、truncate刪除表數(shù)據(jù)后，標(biāo)識(shí)重新恢復(fù)初始狀態(tài)。默認(rèn)為初始值為1，也就是說，truncate之后，再插入一條數(shù)據(jù)，id=1.
其它互聯(lián)網(wǎng)摘抄：
1、寫一張表中有id和name 兩個(gè)字段，查詢出name重復(fù)的所有數(shù)據(jù)，現(xiàn)在列下：
select * from xi a where (a.username) in (select username from xi group by username having count(*) > 1)
2、查詢出所有數(shù)據(jù)進(jìn)行分組之后，和重復(fù)數(shù)據(jù)的重復(fù)次數(shù)的查詢數(shù)據(jù)，先列下：
select count(username) as ’重復(fù)次數(shù)’,username from xi group by username having count(*)>1 order by username desc
3、一下為 查看別人的 結(jié)果，現(xiàn)列下：查詢及刪除重復(fù)記錄的方法大全
1、查找表中多余的重復(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(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)
3、查找表中多余的重復(fù)記錄（多個(gè)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)
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)
(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＂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 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(jì)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(gè)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(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）
(四)
查詢重復(fù)select * from tablename where id in (select id from tablenamegroup by idhaving count(id) > 1)
*******舉例*********
查詢 Sap Business One制造商OMRC表中重復(fù)數(shù)據(jù)(Pass)
select * from omrc
where firmname in (select firmname from omrc group by firmname having count(firmname) > 1)
刪除 Sap Business One制造商OMRC表中重復(fù)數(shù)據(jù)(Pass)
delete from omrc
where FirmName in (select FirmName from omrc group by FirmName having count(FirmName) > 1)
and FirmCode not in (select min(FirmCode) from omrc group by FirmName having count(FirmName )>1)
OMRC為表名，F(xiàn)irmName/FirmCode為字段名。
***刪除或保留一些行數(shù)據(jù)
數(shù)據(jù)庫int001幾個(gè)表OMRC/POR1/RDR1，保留前六行數(shù)據(jù)(操作，出現(xiàn)表錯(cuò)誤，處理后/truncate/再導(dǎo)入)
DELETE OMRC WHERE FirmCode NOT IN(SELECT TOP 6 FirmCode FROM OMRC)
DELETE Por1 WHERE DocEntry NOT IN(SELECT TOP 6 DocEntry FROM Por1)
DELETE RDR1 WHERE DocEntry NOT IN(SELECT TOP 6 DocEntry FROM RDR1)
*****************************
查詢數(shù)據(jù)庫中帶有某個(gè)字段的所有表名
MySQL數(shù)據(jù)庫查詢帶有某個(gè)字段的所有表名：
（1）精確查詢語句如下：
SELECT * FROM information_schema.columns WHERE column_name=’column_name’
（2）模糊匹配查詢
SELECT * FROM information_schema.columns WHERE column_name LIKE ’%column_name%’
Oracle數(shù)據(jù)庫查詢帶有某個(gè)字段的所有表名：
（1）精確查詢語句如下：
SELECT column_name,table_name FROM user_tab_columns WHERE column_name=’column_name’
（2）模糊匹配查詢
SELECT column_name,table_name,FROM user_tab_columns WHERE column_name LIKE ’%column_name%’
SQLServer數(shù)據(jù)庫查詢帶有某個(gè)字段的所有表名：
（1）精確查詢語句如下：
SELECT [name] FROM [庫名].[dbo].sysobjects WHERE id IN (SELECT id FROM [庫名].[dbo].syscolumns WHERE name = ’字段名’)
（2）模糊匹配查詢
SELECT [name] FROM [庫名].[dbo].sysobjects WHERE id IN (SELECT id FROM [庫名].[dbo].syscolumns WHERE name LIKE ’%字段名%’)
|
