sql中删除重复数据

Question

如题所述

Answer 1

SQL Server删除重复行是我们最常见的操作之一，下面就为您介绍六种适合不同情况的SQL Server删除重复行的方法，供您参考。

1.如果有ID字段，就是具有唯一性的字段

delect table where id not in (

select max(id) from table group by col1,col2,col3...
)
group by 子句后跟的字段就是你用来判断重复的条件，如只有col1，那么只要col1字段内容相同即表示记录相同。

2. 如果是判断所有字段也可以这样

select * into #aa from table group by id1,id2,....
delete table
insert into table
select * from #aa
3. 没有ID的情况

select identity(int,1,1) as id,* into #temp from tabel
delect # where id not in (
select max(id) from # group by col1,col2,col3...)
delect table
inset into table(...)
select ..... from #temp
4. col1+','+col2+','...col5 联合主键

select * from table where col1+','+col2+','...col5 in (
select max(col1+','+col2+','...col5) from table
where having count(*)>1
group by col1,col2,col3,col4
)
group by 子句后跟的字段就是你用来判断重复的条件，如只有col1，那么只要col1字段内容相同即表示记录相同。

5.

select identity(int,1,1) as id,* into #temp from tabel
select * from #temp where id in (
select max(id) from #emp where having count(*)>1 group by col1,col2,col3...)
6.

select distinct * into #temp from tablename
delete tablename
go
insert tablename select * from #temp Sqlclub
go
drop table #temp
以上就是SQL Server删除重复行的方法介绍。

Answer 2

CREATE OR REPLACE PROCEDURE distint_data
(
target VARCHAR2,
temp VARCHAR2
)
AS
v_sql VARCHAR2(500);
BEGIN
v_sql:='create table '||temp||' as select distinct * from '||target;
EXECUTE IMMEDIATE v_sql;--首先创建一张临时表
v_sql:='truncate table '||target;
EXECUTE IMMEDIATE v_sql;--清空原表记录
v_sql:='insert into '||target||' select * from '||temp;
EXECUTE IMMEDIATE v_sql;--将临时表的数据倒插回来
v_sql:='drop table '||temp;
EXECUTE IMMEDIATE v_sql;--将临时表删除
END distint_data;
直接输入两个表名就可以进行剔重了。

Answer 3

用delete 命令然后用where 筛选条件

Answer 4

create table #temp (xm varchar(10))

insert into #temp values ('张三')
insert into #temp values ('李四')
insert into #temp values ('王五')
insert into #temp values ('张三')
insert into #temp values ('张三')
insert into #temp values ('李四')
insert into #temp values ('李四')
insert into #temp values ('李四')

delete from #temp where xm in
(select xm from #temp group by xm having count(*)>1)

select * from #temp

drop table #temp

Answer 5

SELECT * FROM USER_INFO WHERE USERID IN (SELECT MAX(USERID) FROM USER_INFO GROUP BY USERID HAVING COUNT(*)=1)