Sql server 重複資料刪除記錄的SQL語句

有兩個意義上的重複記錄，一是完全重複的記錄，也即所有欄位均重複的記錄，二是部分關鍵字段重複的記錄，比如Name欄位重複，而其他欄位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。
如果該表需要重複資料刪除的記錄（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
假設有重複的欄位為Name,Address，要求得到這兩個欄位唯一的結果集
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欄位，實際寫時可以寫在select子句中省去此列）3、部分關鍵字段重複，且記錄中有ID.第一種方法可一次刪除所有重複的..(只保留重複中ID最小的記錄)。
delete from table where id not in ( select min(id) from table group by name)第二種方法每次只重複資料刪除中ID最大的一條記錄。

delete from table where id in ( select max(id) from table group by name having count(*)>1)4、SQL程式刪除declare @max integer,@id integer
declare cur_rows cursor local for select 主欄位,count(*) from 表名 group by 主欄位 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 主欄位 = @id
fetch cur_rows into @id,@max
end
close cur_rows
set rowcount 0

自己還得出的辦法：
select   *   from   user1     where   [id]   not   in   (select   top   1
  [id]   from   user1   a   where   name=user1.name)  
  --刪就這樣寫  
  delete   from   user1     where   [id]   not   in   (select   top   1   [id]   from   user1   a   where   name=user1.name)
或 delete from user where id not in ( select max(id) from user where name=user.name)
delete [user] where id not in (select max(id) from [user] group by name having count(*) > 1)
max 或 min看具體情況而論。

其他方法：
----A:保留id最大的行,刪除其它行  
  --方法1  
  delete   [user]   from   [user]   t    
  inner   join(select   name,max(id)   as   id   from   [user]   group   by   name)   a  
  on   t.name   =   a.name   and   t.id   <>   a.id  
  --方法2  
  delete   [user]   from   [user]   t  
  where     exists(select   *   from   [user]   where   name   =   t.name   and   id   >   t.id)  
   
  ----B:保留id最小的行,刪除其它行  
  --方法1  
  delete   [user]   from   [user]   t    
  inner   join(select   name,min(id)   as   id   from   [user]   group   by   name)   a  
  on   t.name   =   a.name   and   t.id   <>   a.id  
  --方法2  
  delete   [user]   from   [user]   t  
  where     exists(select   *   from   [user]   where   name   =   t.name   and   id   <   t.id)  
   
  ----C:刪除所有重複的name行,一行也不留  
  delete   [user]   from   [user]   t    
  inner   join    
  (select   id   from   [user]   a   where   exists(select   *   from  
[user]   where   name   =   a.name   group   by   name   having  
count(*)   >   1))   as   b  
  on   t.id   =   b.id有兩個意義上的重複記錄，一是完全重複的記錄，也即所有欄位均重複的記錄，二是部分關鍵字段重複的記錄，比如Name欄位重複，而其他欄位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。
如果該表需要重複資料刪除的記錄（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
假設有重複的欄位為Name,Address，要求得到這兩個欄位唯一的結果集
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欄位，實際寫時可以寫在select子句中省去此列）3、部分關鍵字段重複，且記錄中有ID.第一種方法可一次刪除所有重複的..(只保留重複中ID最小的記錄)。
delete from table where id not in ( select min(id) from table group by name)第二種方法每次只重複資料刪除中ID最大的一條記錄。

delete from table where id in ( select max(id) from table group by name having count(*)&gt;1)4、SQL程式刪除declare @max integer,@id integer
declare cur_rows cursor local for select 主欄位,count(*) from 表名 group by 主欄位 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 主欄位 = @id
fetch cur_rows into @id,@max
end
close cur_rows
set rowcount 0

自己還得出的辦法：
select   *   from   user1     where   [id]   not   in   (select   top   1
  [id]   from   user1   a   where   name=user1.name)  
  --刪就這樣寫  
  delete   from   user1     where   [id]   not   in   (select   top   1   [id]   from   user1   a   where   name=user1.name)
或 delete from user where id not in ( select max(id) from user where name=user.name)
delete [user] where id not in (select max(id) from [user] group by name having count(*) > 1)
max 或 min看具體情況而論。

其他方法：
----A:保留id最大的行,刪除其它行  
  --方法1  
  delete   [user]   from   [user]   t    
  inner   join(select   name,max(id)   as   id   from   [user]   group   by   name)   a  
  on   t.name   =   a.name   and   t.id   <>   a.id  
  --方法2  
  delete   [user]   from   [user]   t  
  where     exists(select   *   from   [user]   where   name   =   t.name   and   id   >   t.id)  
   
  ----B:保留id最小的行,刪除其它行  
  --方法1  
  delete   [user]   from   [user]   t    
  inner   join(select   name,min(id)   as   id   from   [user]   group   by   name)   a  
  on   t.name   =   a.name   and   t.id   <>   a.id  
  --方法2  
  delete   [user]   from   [user]   t  
  where     exists(select   *   from   [user]   where   name   =   t.name   and   id   <   t.id)  
   
  ----C:刪除所有重複的name行,一行也不留  
  delete   [user]   from   [user]   t    
  inner   join    
  (select   id   from   [user]   a   where   exists(select   *   from  
[user]   where   name   =   a.name   group   by   name   having  
count(*)   >   1))   as   b  
  on   t.id   =   b.id