alter table BLE add id int identity(1,1)delete BLE a where exists(select 1 from BLE where a.code=code and id<a.id)
BLE中有一个字段CODE(不是主键字段),CODE字段里面可能有很多组重复的数据,现在我想把那些重复的数据就留一条,其他的删除,要的那条数据随便哪条都可以,只要留下重复中的其中一条就可以了,请问怎么删除?delete from ble where 主键 not in (select min(主键) from ble group by code)
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?谢谢! 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(*)>1)
delete a from BLE a where not exists(select 1 from BLE where a.主键字段>主键字段 and a.code=code)
请参阅下例一张表里面以两个字段为唯一字段,当几条记录的这两个字段完全相同时,需要删除重复项,如下表 a b c d 1 2 3 4 1 5 3 5 1 2 7 9 以a、b为唯一字段,第一条和第三条的a、b完全相同,所以,需要删除第一条记录1 2 3 4 或者第三条记录1 2 7 9 即如下结果: a b c d 1 2 3 4 1 5 3 5 或 a b c d 1 5 3 5 1 2 7 9请问各位大侠这种sql语句怎么写 CREATE TABLE Tb1(id int, [a] varchar(255), [b] varchar(255), [c] varchar(255), [d] varchar(255)) INSERT Tb1(id, [a], [b], [c], [d]) SELECT 1, '1','2','3','4' UNION ALL SELECT 2, '1','5','3','5' UNION ALL SELECT 3, '1','2','7','9' UNION ALL SELECT 4, '1','4','7','6'delete Tb1 where [id] not in (select max([id]) from Tb1 group by a,b ) select * from tb1
drop table tb1如果要同时删除第一和第三行 即如下结果: a b c d 1 5 3 5语句如下:delete m from tb t inner join ( select a ,b from tb group by a , b having count(*)>1 )n on m.a = n.a and m.b = n.b 或 delete * from tb as m, ( select a ,b from tb group by a , b having count(*)>1 )n where m.a = n.a and m.b = n.b
create table t (code int )insert into t select 2 union all select 2 union all select 2 alter table t add id int identity(1,1)delete t where id not in ( select id from t a where not exists(select 1 from t where a.code=code and id<a.id) )select * from t code id ----------- ----------- 2 1(所影响的行数为 1 行)
ordelete ble where name not in(select min(name) from ble group by code)or delete ble where name not in(select max(name) from ble group by code)
--1 delete a from ble a where exists(select 1 from ble b where a.code=b.code and a.id<b.id)---2 delete a from ble a where id not in ( select min id from ble group by code)
add id int identity(1,1)delete BLE a
where exists(select 1 from BLE where a.code=code and id<a.id)
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(*)>1)
a b c d
1 2 3 4
1 5 3 5
1 2 7 9
以a、b为唯一字段,第一条和第三条的a、b完全相同,所以,需要删除第一条记录1 2 3 4 或者第三条记录1 2 7 9
即如下结果:
a b c d
1 2 3 4
1 5 3 5
或
a b c d
1 5 3 5
1 2 7 9请问各位大侠这种sql语句怎么写
CREATE TABLE Tb1(id int, [a] varchar(255), [b] varchar(255), [c] varchar(255), [d] varchar(255))
INSERT Tb1(id, [a], [b], [c], [d])
SELECT 1, '1','2','3','4'
UNION ALL SELECT 2, '1','5','3','5'
UNION ALL SELECT 3, '1','2','7','9'
UNION ALL SELECT 4, '1','4','7','6'delete Tb1 where [id] not in (select max([id]) from Tb1 group by a,b )
select * from tb1
drop table tb1如果要同时删除第一和第三行
即如下结果:
a b c d
1 5 3 5语句如下:delete m from tb t
inner join
(
select a ,b
from tb
group by a , b
having count(*)>1
)n
on m.a = n.a and m.b = n.b
或
delete * from tb as m,
(
select a ,b
from tb
group by a , b
having count(*)>1
)n
where m.a = n.a and m.b = n.b
(code int
)insert into t
select 2 union all
select 2 union all
select 2 alter table t
add id int identity(1,1)delete t
where id not in
(
select id from t a
where not exists(select 1 from t where a.code=code and id<a.id)
)select * from t
code id
----------- -----------
2 1(所影响的行数为 1 行)
where name not in(select min(name) from ble group by code)or delete ble
where name not in(select max(name) from ble group by code)
--1
delete a from ble a
where exists(select 1 from ble b where a.code=b.code and a.id<b.id)---2
delete a from ble a
where id not in (
select min id from ble
group by code)