SQL重復記錄查詢 查詢多個字段、多表查詢、刪除重復記錄的方法，sql字段

SQL重復記錄查詢 查詢多個字段、多表查詢、刪除重復記錄的方法，sql字段

SQL重復記錄查詢

1、查找表中多余的重復記錄，重復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) 

例二： 

select * from testtable 
where numeber in (select number from people group by number having count(number) > 1 ) 

可以查出testtable表中number相同的記錄  

2、刪除表中多余的重復記錄，重復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、查找表中多余的重復記錄（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、刪除表中多余的重復記錄（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、查找表中多余的重復記錄（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”， 

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”值存在重復的項； 

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 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  

有兩個意義上的重復記錄，一是完全重復的記錄，也即所有字段均重復的記錄，二是部分關鍵字段重復的記錄，比如Name字段重復，而其他字段不一定重復或都重復可以忽略。  

1、對於第一種重復，比較容易解決，使用 

select distinct * from tableName 

就可以得到無重復記錄的結果集。  

如果該表需要刪除重復的記錄（重復記錄保留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 

發生這種重復的原因是表設計不周產生的，增加唯一索引列即可解決。  

2、這類重復問題通常要求保留重復記錄中的第一條記錄，操作方法如下  

假設有重復的字段為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不重復的結果集（但多了一個autoID字段，實際寫時可以寫在select子句中省去此列）  

(四)  

查詢重復 

select * from tablename where id in ( 
 
select id from tablename  
 
group by id  
 
having count(id) > 1 
 
) 

以上就是小編為大家帶來的SQL重復記錄查詢 查詢多個字段、多表查詢、刪除重復記錄的方法的全部內容了，希望對大家有所幫助，多多支持幫客之家~