Deleting duplicate records

Question

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I have tried a sql query to find the number of duplicate records in a table:

SQL

select count(*) from table_name a
where rowid >(select min(rowid)
                        from table_name b
                     where a.column1=b.column1
and a.Column2 = b.Column2)

This returned me a result of 1203 rows.
Now when i try to run the below query to delete these rows, the application hangs and stops responding.

SQL

delete from table_name a
where rowid >select min(rowid)
                        from table_name b
                     where a.column1=b.column1
and a.column2= b.column2)

Is there any other way to do it? Please help

Posted 23-May-11 0:23am

Prathibha Sharat

Updated 23-May-11 5:42am

thatraja

v2

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Mahendra.p25 · Answer 1 · 2011-05-23T01:09:00

Solution 3

try this Link

sql-server-delete-duplicate-records-rows[^]

Posted 23-May-11 1:09am

Mahendra.p25

Prerak Patel · Answer 2 · 2011-05-23T00:38:00

Solution 1

Have a look at following article
http://support.microsoft.com/kb/139444[^]

Posted 23-May-11 0:38am

Prerak Patel

mhwasim · Answer 3 · 2011-05-23T01:00:00

Solution 2

1. Create another table temp or physical for temporary use
2. Insert distinct record in that table
3. Trunace the existing one which has duplicate rows
4. Insert rown back form temp table to original table
5. truncate / delete temp table

If data is large then use another physical table with same structure as of original....

Thanks

Posted 23-May-11 1:00am

mhwasim

v2

Comments

Prathibha Sharat 23-May-11 9:45am

Hi,
Thanks for the reply. Can you also help me with the commands i need to use as I am not very familiar with SQL.

thatraja · Answer 4 · 2011-05-23T05:47:00

Solution 4

Check these CP Tips/Tricks

Remove Duplicate Rows from a Table in SQL Server[^]

How to remove duplicate rows in SQL Server 2005 when no key is present - 1[^]

How to remove duplicate rows in SQL Server 2005 when no key is present - 2[^]

Remove duplicate records from SQL tables[^]

Posted 23-May-11 5:47am

thatraja

Comments

Prathibha Sharat 24-May-11 9:35am

The steps mentioned in the procedure asks me to add an identity column but I am not able to do so:-
alter table table_name
add column_name int not null Identity(1,1);
But this doesnt work. Any solution?