1.表中有id和name 两个字段，查询出name重复的所有数据
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1
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select
*
from
xi a
where
(a.username)
in
(
select
username
from
xi
group
by
username
having
count
(*) > 1)
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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：
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1
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select
count
(username)
as
'重复次数'
,username
from
xi
group
by
username
having
count
(*)>1
order
by
username
desc
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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
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1
2
|
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
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1
2
3
|
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）
|
1
2
|
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
|
1
2
3
|
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
|
1
2
3
|
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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1
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
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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
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1
2
3
4
|
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
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1
2
3
|
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
|
1
|
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
|
1
|
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
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2
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4
|
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
)
|