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教你SQL语句删除重复记录 (2)

发布时间:2019-09-13 20:25:37

方案3: 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_distcreate 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asbegindeclare @max integer,@id varchar(30) ,@sql varchar(7999) ,@type integerselect @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_keyif @type=56select @sql = 'delete from '+@t_name+' where ' + @f_key+' = '+ @id if @type=167select @sql = 'delete from '+@t_name+' where ' + @f_key+' = '+''''+ @id +'''' exec(@sql)fetch cur_rows into @id,@max end close cur_rows deallocate cur_rowsset rowcount 0endselect * from systypesselect * from syscolumns where id = object_id('a_dist')

方案4: 可以用IGNORE_DUP_KEY: create table dup (id int identity not null,name varchar(50)not null)goinsert 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')goselect *from dupgocreate table tempdb..wk(id int not null, name varchar(50)not null)gocreate unique index idx_remove_dup on tempdb..wk(name)with IGNORE_DUP_KEY goINSERT INTO tempdb..wk (id, name)select id, namefrom dupgoselect *from tempdb..wkgodelete from dupgoset identity_insert dup onINSERT INTO dup (id, name)select id, namefrom tempdb..wkgoset identity_insert dup offgoselect *from dupgo

注:这里delete原表,再加入不重复的值。也可以通过join只delete原表中重复的值。

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