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sql排除相同数据

发布时间: 2022-10-16 01:51:08

sql去除重复的项

首先你是要去除,也就是说删除数据,还是只是查询不重复数据,如果是删除重复数据
就不该用select;暂且认为
你是查询数据;
其次,你的意思应该是去除
b
列中重复的数据,但是你没给定
确切的条件,比如,b列出现了重复数据,那你是要保留那一条呢,
再就是你那个查询:select
distinct
b,a,c
from
table
的意思是将三列
都重复的去除,只有三列都重复了
才会去除。你这里的数据明显
不存在三个列都重复的数据,所以查询
出来的还是原
表中的数据。

⑵ SQL 怎么去除完全重复的数据

用SQL语句,删除掉重复项只保留一条

在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢
1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断
select * from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)

2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录
delete from people
where peopleName in (select peopleName from people group by peopleName having count(peopleName) > 1)
and peopleId not in (select min(peopleId) from people group by peopleName having count(peopleName)>1)

3、查找表中多余的重复记录(多个字段)
select * from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)

4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段),不包含rowid最小的记录
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)
6.消除一个字段的左边的第一位:
update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'
7.消除一个字段的右边的第一位:
update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'
8.假删除表中多余的重复记录(多个字段),不包含rowid最小的记录
update vitae set ispass=-1
where peopleId in (select peopleId from vitae group by peopleId

⑶ SQL语句怎么删除重复的数据

删除重复的数据
delete
from
tb
where
id
not
in
(
select
id
from
(select
fileSize,fileName
,max(id)
id
from
tb
group
by
filesize,filename
)
a
)
现在完成了重复数据的删除,主要是利用了找出某个分组中最大的那个id,其中包括了所有不重复的id,然后使用not
in将需要保留的排除。

⑷ 如何用SQL语句删除两个表中相同的记录

1,首先创建一个表,并在表中插入重复的记录,如下图所示。

⑸ sql查询语句怎么排除重复数据

select
id,
name,
memo
from
A
where
id
in
(select
id
from
A
group
by
id
having
count(1)
>=
2)
select
id,
name,
memo
from
A
where
id
in
(select
id
from
A
group
by
id
having
count(1)
>=
2)

⑹ sql 怎样删除一列中相同的数据

sql清除一列数据分为两种情况,一种是将一列的数据清空,另一种是将某列名删除。
工具:SQL
Server
2008
R2
表中数据如下:
一、将数据清空(删除begin_date列的数据,使之为空)
update
test
set
begin_date=null;
执行后结果:
二、将列名删除(删除begin_date列,使之在表中不存在)
alter
table
test
drop
column
begin_date;
执行后结果(可发现begin_date列已经删除):

⑺ sql 如何过滤重复记录

问题背景

在一个多表查询的sql中正常情况下产生的数据都是唯一的,但因为数据库中存在错误(某张表中存在相同的外键ID)导致我这边查询出来的数据就会有重复的问题

下面结果集中UserID:15834存在多个

参考:

MSDN: OVER 子句 (Transact-SQL)

stackoverflow sql query distinct with Row_Number

SQL Trick: row_number() is to SELECT what dense_rank() is to SELECT DISTINCT

⑻ sql如何删除重复数据

sql查询去除重复值语句
sql 单表/多表查询去除重复记录
单表distinct
多表group by
group by 必须放在 order by 和 limit之前,不然会报错
************************************************************************************
1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断
select * from people
where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段)
select * from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录
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、查找表中多余的重复记录(多个字段),不包含rowid最小的记录
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(*)>

⑼ sql语句查询过滤重复数据

1、查找表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断

复制代码代码如下:

select * from people
where peopleId in (select peopleId from people group by peopleId having count

(peopleId) > 1)

2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录

复制代码代码如下:

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)

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