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delete dublicate rows

Author

Topic

pascal_jimi
Posting Yak Master

167 Posts

Posted - 2014-01-27 : 02:10:59

declare @a1 table
(id int not null identity(1,1),
phone decimal(18,0),
adress nvarchar(100))

insert @a1
(phone,adress)
values
(111,'new york')
insert @a1
(phone,adress)
values
(111,'new york')
insert @a1
(phone,adress)
values
(111,'new york')
insert @a1
(phone,adress)
values
(222,'maxico')
insert @a1
(phone,adress)
values
(222,'mexico')

select*from @a1
id phone adress
----------- --------------------------------------- ----------------------------------------------------------------------------------------------------
1 111 new york
2 111 new york
3 111 new york
4 222 maxico
5 222 mexico

select phone,count(phone) as say from @a1 group by phone having count(phone)>1

phone say
--------------------------------------- -----------
111 3
222 2

how can I remove duplicate phone

for exmaple

after delete

select*from @a1

select*from @a1
id phone adress
----------- --------------------------------------- ----------------------------------------------------------------------------------------------------
1 111 new york
4 222 maxico

I wrote this to show for example
in my real table have 50000 rows
and
1751 dublicate rows

http://sql-az.tr.gg/

gecew
Starting Member

10 Posts

Posted - 2014-01-27 : 05:02:26

select * from table t1 where exists (select 'x' from table t2
where t1.phone=t2.phone and t1.id>t2.id)

DELETE t1 from table t1 where exists (select 'x' from table t2 where t1.phone=t2.phone and t1.id>t2.id)

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2014-01-27 : 07:19:03

see below illustration


declare @a1 table
(id int not null identity(1,1),
phone decimal(18,0),
adress nvarchar(100))

insert @a1
(phone,adress)
values 
(111,'new york')
insert @a1
(phone,adress)
values 
(111,'new york')
insert @a1
(phone,adress)
values 
(111,'new york')
insert @a1
(phone,adress)
values 
(222,'maxico')
insert @a1
(phone,adress)
values 
(222,'mexico')

delete t
from (select row_number() over (partition by phone order by id ) as seq from @a1)t
where seq > 1

select * from @a1


output
----------------------------
id	phone	adress
----------------------------
1	111	new york
4	222	maxico

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/
https://www.facebook.com/VmBlogs

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