sql 查出一张表中重复的所有记录数据
1.表中有id和title 两个字段,查询出title重复的所有数据
select * from ithome a where (a.title) in (select title from ithome group by title having count(*) > 1)
2、查询出所有数据进行分组之后,和重复数据的重复次数的查询数据,先列下:
select count(id) as '重复次数',title from ithome group by title having count(*)>1 order by title desc
3、一下为 查看别人的 结果,现列下:查询及删除重复记录的方法大全
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 ithome
where title in (select title from ithome group by title having count(title) > 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)
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
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)
(二)
比方说
在A表中存在一个字段“name”,
而且不同记录之间的“name”值有可能会相同,
现在就是需要查询出在该表中的各记录之间,“name”值存在重复的项;
1
|
Select Name , Count (*) From A Group By Name Having Count (*) > 1 |
如果还查性别也相同大则如下:
1
|
Select Name ,sex, Count (*) From A Group By Name ,sex Having Count (*) > 1 |
(三)
方法一
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2
3
4
5
6
7
8
9
10
11
|
declare @ max integer ,@id integer declare cur_rows cursor local for select 主字段, count (*) from 表名 group by 主字段 having count (*) >; open cur_rows fetch cur_rows into @id,@maxwhile @@fetch_status=0 begin select @ max = @ max -1 set rowcount @ max delete from 表名 where 主字段 = @id fetch cur_rows into @id,@maxend close cur_rows set rowcount 0 |
方法二"重复记录"有两个意义上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,二是部分关键字段重复的记录,比如Name字段重复,而其他字段不一定重复或都重复可以忽略。
1、对于第一种重复,比较容易解决,使用
1
|
select distinct * from tableName |
就可以得到无重复记录的结果集。
如果该表需要删除重复的记录(重复记录保留1条),
可以按以下方法删除
select
distinct
*
into
#Tmp
from
tableName
drop
table
tableName
select
*
into
tableName
from
#Tmp
drop
table
#Tmp
发生这种重复的原因是表设计不周产生的,增加唯一索引列即可解决。
2、这类重复问题通常要求保留重复记录中的第一条记录,操作方法如下 假设有重复的字段为Name,Address,要求得到这两个字段唯一的结果集
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)
最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)
(四)查询重复
select
*
from
tablename
where
id
in
(
select
id
from
tablenamegroup
by
idhaving
count
(id) > 1)
对一个字段查找重复记录
根据sample_code字段找到重复记录
SELECT
*
FROM
tb_table
WHERE
sample_code
IN
(
SELECT
sample_code
FROM
tb_table
GROUP
BY
sample_code
HAVING
COUNT
(sample_code) > 1 )
对多个字段查找重复记录(这里以2个为例)
根据name和code字段找到重复记录
SELECT
*
from
(
SELECT
*, CONCAT(
name
,code)
as
nameAndCode
from
tb_table) t
WHERE
t.nameAndCode
in
(
SELECT
nameAndCode
from
(
SELECT
CONCAT(
name
,code)
as
nameAndCode
from
tb_table) tt
GROUP
BY
nameAndCode
HAVING
count
(nameAndCode) > 1
)
简单方法实现
create table ithome_copy1314 select * from ithome
where id in (
select max(id) from ithome group by title
)drop table ithome
ALTER TABLE ithome_copy1314 RENAME TO ithome;