四种SQL语句删除重复记录的方法

select [标志字段id],count(*) into temp1 from [表名]
group by [标志字段id]
having count(*)>1 
 
 
 

insert temp1
select [标志字段id],count(*) from [表名]
group by [标志字段id]
having count(*)=1  
  

select * into temp2 from [表名]
where 标志字段id in(select 标志字段id from temp1)  
 
 

insert [表名]
select * from temp2  
  

drop table temp1
drop table temp2 
  

declare @max integer,@id integer
declare cur_rows cursor local for 
select id,count(*) from 表名 group by id 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 id = @id
fetch cur_rows into @id,@max
end
close cur_rows
set rowcount 0
 
 
 
 
 
 

create table a_dist(id int,name varchar(20)) 
 
 
insert into a_dist values(1,'abc')
insert into a_dist values(1,'abc')
insert into a_dist values(1,'abc')
insert into a_dist values(1,'abc')
exec up_distinct 'a_dist','id'
select * from a_dist
create procedure up_distinct(@t_name varchar(30)
,@f_key varchar(30))
--f_key表示是分组字段﹐即主键字段
as
begin
declare @max integer,@id varchar(30) ,
@sql varchar(7999) ,@type integer
select @sql = 'declare cur_rows cursor 
for select '+@f_key+' ,count(*) from ' 
+@t_name +' group by ' +@f_key +' having count(*) > 1'
exec(@sql)
open cur_rows 
fetch cur_rows into @id,@max 
while @@fetch_status=0 
begin 
select @max = @max -1 
set rowcount @max 
select @type = xtype from syscolumns 
where id=object_id(@t_name) and name=@f_key
if @type=56
select @sql = 'delete from '+@t_name+' 
where ' + @f_key+' = '+ @id 
if @type=167 
 
select @sql = 'delete from '+@t_name+' 
where ' + @f_key+' = '+''''+ @id +'''' 
exec(@sql)
fetch cur_rows into @id,@max 
end 
close cur_rows 
deallocate cur_rows
set rowcount 0
end
select * from systypes
select * from syscolumns where 
id = object_id('a_dist')


 方法4：


可以用IGNORE_DUP_KEY：  
 
 
 

create table dup (id int identity not null,
name varchar(50)not null)
go
insert into dup(name) values ('abc')
insert into dup(name) values ('abc')
insert into dup(name) values ('abc')
insert into dup(name) values ('abc')
insert into dup(name) values ('abc')
insert into dup(name) values ('abc')
insert into dup(name) values ('abc')
insert into dup(name) values ('cdefg')
insert into dup(name) values ('xyz')
insert into dup(name) values ('xyz')
go
select *
from dup
go
create table tempdb..wk(id int not null, 
name varchar(50)not null)
go
create unique index idx_remove_dup 
on tempdb..wk(name)
with IGNORE_DUP_KEY 
go
INSERT INTO tempdb..wk (id, name)
select id, name
from dup
go
select *
from tempdb..wk
go
delete from dup
go
set identity_insert dup on
INSERT INTO dup (id, name)
select id, name
from tempdb..wk 
 
 
go
set identity_insert dup off
go
select *
from dup
go
  




注释：此处delete原表，再加入不重复的值。大家也可以通过join只delete原表中重复的值。