Deleting Dulpicate row

Posted on 2001-09-10
Last Modified: 2008-02-07
Dear All,
Is there Any query ,Which will Delete Duplicate Rows from the table which does not  have primary key..please
Help me out
Question by:skumaravelan
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Expert Comment

ID: 6473197
What database are you using?

Accepted Solution

kdg2000 earned 50 total points
ID: 6473256
Algorithm 1:
1. Opens Recordset of all unique values
2. In cycle there is an exhaustive search of all values.
3. In cycle: We define how many counterparts of current value in the table. If them more than 1, then is remembered current value, we delete all and is added it(him).
4. End of cycle
5. Closing RecordSet.

Algorithm 2:
1. Opens Recordset of all values sorted on increase
2. We create a variable, in which the previous value is stored
2. In cycle there is an exhaustive search of all values.
3. In cycle: whether We define equally given data previous. If yes - then is deleted it, differently - variable is assigned current value
4. End of cycle
5. Closing RecordSet.

In SQL Server it is done(made) so:

declare @S as varchar (8000)
/* The cursor of the necessary type */ is declared
declare Data_Pr_F scroll cursor
/* Choice of not repeating values */
for select distinct DuplicateRows from [table]
open Data_Pr_F
FETCH FIRST from Data_Pr_F into @S
      /* Check of the end of the table */
      while @@ fetch_status < > -1
           /* If there is more than one counterpart, then all values are deleted and one unique value is added */
           if (select count (DuplicateRows) from [table]) > 1
                delete * from [table] where DuplicateRows = S
                insert into [table] values (@S)
           /* Transition to the following string(line) */
           FETCH next from Data_Pr_F into @S
/* Deleting the cursor */
LVL 27

Expert Comment

ID: 6473756
maybe also

step one: create a table with none duplicate values
  create table tmp as Select distinct * from originaltable;

step two: empty sourcetable
  delete from originaltable;

step three: store back
  insert into originaltable select * from tmp;

step four: drop tmp-table
  drop table tmp;

(may not work on all databases)

meikl ;-)
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Author Comment

ID: 6473771
Dear All,
I have tried al the option u all said befoe.My question is,is there any way to do the same with writing a procedure or function
LVL 27

Expert Comment

ID: 6473849
it would help,
if you let us know the database you have

Author Comment

ID: 6473985
Hi kretzschmar,
I have oracle 8 as my database.

Expert Comment

ID: 6475728
Oracle 8 is very similar on MS SQL Server. Some finishings are certainly necessary. For example environment variable @@ fetch_status for certain is not present in Oracle, but 100 % there are a similar variable. Anyway standard SQL 92 is uniform both for Oracle and for MS SQL Server.
I think these small finishings as you seem to me can make.

Author Comment

ID: 6475813
Dear KDq2000,
Thank You very much for ur valuable reply.

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