查詢同一表內多字段同時重複記錄的SQL語句

 

好比如今有一人員表 （表名：peosons）
若想將姓名、×××號、住址這三個字段徹底相同的記錄查詢出來
select p1.* from persons p1,persons p2 where p1.id<>p2.id and p1.cardid = p2.cardid and p1.pname = p2.pname and p1.address = p2.address

能夠實現上述效果．

幾個刪除重複記錄的SQL語句

1.用rowid方法

2.用group by方法

3.用distinct方法


1。用rowid方法

據據Oracle帶的rowid屬性，進行判斷，是否存在重複,語句以下：
查數據:
select * from table1 a where rowid !=(select max(rowid)
from table1 b where a.name1=b.name1 and a.name2=b.name2......)
刪數據：
delete from table1 a where rowid !=(select max(rowid)
from table1 b where a.name1=b.name1 and a.name2=b.name2......)

2.group by方法

查數據:
select count(num), max(name) from student --列出重複的記錄數，並列出他的name屬性
group by num
having count(num) >1 --按num分組後找出表中num列重複，即出現次數大於一次
刪數據：
delete from student
group by num
having count(num) >1
這樣的話就把全部重複的都刪除了。

3.用distinct方法 -對於小的表比較有用

create table table_new as select distinct * from table1 minux
truncate table table1;
insert into table1 select * from table_new;



查詢及刪除重複記錄的方法大全

一、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)


二、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)


三、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)


四、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)


五、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)


(二)
比方說
在A表中存在一個字段「name」，
並且不一樣記錄之間的「name」值有可能會相同，
如今就是須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
若是還查性別也相同大則以下:
Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1


(三)
方法一
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
＂重複記錄＂有兩個意義上的重複記錄，一是徹底重複的記錄，也即全部字段均重複的記錄，二是部分關鍵字段重複的記錄，好比Name字段重複，而其餘字段不必定重複或都重複能夠忽略。


一、對於第一種重複，比較容易解決，使用
select distinct * from tableName
就能夠獲得無重複記錄的結果集。
若是該表須要刪除重複的記錄（重複記錄保留1條），能夠按如下方法刪除
select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp
發生這種重複的緣由是表設計不周產生的，增長惟一索引列便可解決。


二、這類重複問題一般要求保留重複記錄中的第一條記錄，操做方法以下
假設有重複的字段爲Name,Address，要求獲得這兩個字段惟一的結果集
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即獲得了Name，Address不重複的結果集（但多了一個autoID字段，實際寫時能夠寫在select子句中省去此列）


(四)
查詢重複
select * from tablename where id in (
select id from tablename
group by id
having count(id) > 1
)