1.表中有id和name 兩個字段，查詢出name重複的全部數據sql
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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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二、查詢出全部數據進行分組以後，和重複數據的重複次數的查詢數據，先列下：ide
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select
count
(username)
as
'重複次數'
,username
from
xi
group
by
username
having
count
(*)>1
order
by
username
desc
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三、一下爲 查看別人的 結果，現列下：查詢及刪除重複記錄的方法大全fetch
一、查找表中多餘的重複記錄，重複記錄是根據單個字段（peopleId）來判斷spa
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2
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select
*
from
people
where
peopleId
in
(
select
peopleId
from
people
group
by
peopleId
having
count
(peopleId) > 1)
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二、刪除表中多餘的重複記錄，重複記錄是根據單個字段（peopleId）來判斷，只留有rowid最小的記錄.net
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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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三、查找表中多餘的重複記錄（多個字段）設計
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2
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select
*
from
vitae a
where
(a.peopleId,a.seq)
in
(
select
peopleId,seq
from
vitae
group
by
peopleId,seq
having
count
(*) > 1)
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四、刪除表中多餘的重複記錄（多個字段），只留有rowid最小的記錄code
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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)
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五、查找表中多餘的重複記錄（多個字段），不包含rowid最小的記錄htm
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2
3
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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)
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(二)索引
比方說ip
在A表中存在一個字段「name」，
並且不一樣記錄之間的「name」值有可能會相同，
如今就是須要查詢出在該表中的各記錄之間，「name」值存在重複的項；
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1
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Select
Name
,
Count
(*)
From
A
Group
By
Name
Having
Count
(*) > 1
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若是還查性別也相同大則以下:
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1
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Select
Name
,sex,
Count
(*)
From
A
Group
By
Name
,sex
Having
Count
(*) > 1
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(三)
方法一
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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＂重複記錄＂有兩個意義上的重複記錄，一是徹底重複的記錄，也即全部字段均重複的記錄，二是部分關鍵字段重複的記錄，好比Name字段重複，而其餘字段不必定重複或都重複能夠忽略。
一、對於第一種重複，比較容易解決，使用
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1
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select
distinct
*
from
tableName
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就能夠獲得無重複記錄的結果集。
若是該表須要刪除重複的記錄（重複記錄保留1條），
能夠按如下方法刪除
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select
distinct
*
into
#Tmp
from
tableName
drop
table
tableName
select
*
into
tableName
from
#Tmp
drop
table
#Tmp
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發生這種重複的緣由是表設計不周產生的，增長惟一索引列便可解決。
二、這類重複問題一般要求保留重複記錄中的第一條記錄，操做方法以下 假設有重複的字段爲Name,Address，要求獲得這兩個字段惟一的結果集
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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)
|
最後一個select即獲得了Name，Address不重複的結果集（但多了一個autoID字段，實際寫時能夠寫在select子句中省去此列）
(四)查詢重複
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1
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select
*
from
tablename
where
id
in
(
select
id
from
tablenamegroup
by
idhaving
count
(id) > 1)
|
對一個字段查找重複記錄
根據sample_code字段找到重複記錄
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SELECT
*
FROM
tb_table
WHERE
sample_code
IN
(
SELECT
sample_code
FROM
tb_table
GROUP
BY
sample_code
HAVING
COUNT
(sample_code) > 1 );
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對多個字段查找重複記錄（這裏以2個爲例）
根據name和code字段找到重複記錄
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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
)
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多字段查，刪
查
SELECT * FROM vip_goodsdiscount WHERE (goodsId,cardType) IN (SELECT goodsId,cardType FROM vip_goodsdiscount GROUP BY goodsId,cardType HAVING COUNT(*) > 1)
ORDER BY goodsId DESC
刪
DELETE FROM vip_goodsdiscount WHERE (vip_goodsdiscount.goodsId,vip_goodsdiscount.cardType) IN (SELECT * FROM (SELECT goodsId,cardType FROM vip_goodsdiscount GROUP BY goodsId,cardType HAVING COUNT(*) > 1) AS t1 ) AND id NOT IN (SELECT * FROM (SELECT MIN(id) FROM vip_goodsdiscount GROUP BY goodsId,cardType HAVING COUNT(*)>1) AS t2)