SQL反復記載查詢 查詢多個字段、多表查詢、刪除反復記載的辦法

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SQL反復記載查詢

1、查找表中過剩的反復記載，反復記載是依據單個字段（peopleId）來斷定 

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雷同的記載  

2、刪除表中過剩的反復記載，反復記載是依據單個字段（peopleId）來斷定，只留有rowid最小的記載 

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、查找表中過剩的反復記載（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、刪除表中過剩的反復記載（多個字段），只留有rowid最小的記載 

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、查找表中過剩的反復記載（多個字段），不包括rowid最小的記載 

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) 

比喻說 

在A表中存在一個字段“name”， 

並且分歧記載之間的“name”值有能夠會雷同， 

如今就是須要查詢出在該表中的各記載之間，“name”值存在反復的項； 

Select Name,Count(*) From A Group By Name Having Count(*) > 1 

假如還查性別也雷同年夜則以下： 

Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1 

(三) 

辦法一 

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 

辦法二  

有兩個意義上的反復記載，一是完整反復的記載，也即一切字段均反復的記載，二是部門症結字段反復的記載，好比Name字段反復，而其他字段紛歧定反復或都反復可以疏忽。  

1、關於第一種反復，比擬輕易處理，應用 

select distinct * from tableName 

便可以獲得無反復記載的成果集。  

假如該表須要刪除反復的記載（反復記載保存1條），可以按以下辦法刪除 

select distinct * into #Tmp from tableName 
 
drop table tableName 
 
select * into tableName from #Tmp 
 
drop table #Tmp 

產生這類反復的緣由是表設計不周發生的，增長獨一索引列便可處理。  

2、這類反復成績平日請求保存反復記載中的第一筆記錄，操作辦法以下  

假定有反復的字段為Name,Address，請求獲得這兩個字段獨一的成果集 

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) 

最初一個select即獲得了Name，Address不反復的成果集（但多了一個autoID字段，現實寫時可以寫在select子句中省去此列）  

(四)  

查詢反復 

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

以上就是小編為年夜家帶來的SQL反復記載查詢 查詢多個字段、多表查詢、刪除反復記載的辦法的全體內容了，願望對年夜家有所贊助，多多支撐~