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Removing repeated values in a table

What is the most efficient way of removing repeated values in a table? Currently the script I am using only removes...

duplicates, so it must be run multiple times if the records are triplicated, etc.

Let's say for example that table T has a column C that repeats several times. You want to remove the repeated values.

1) Create a temporary view.

    create view V
        as select count(*) as CNT , C
           from T
           group by C
           having count(*) > 1;
2) Create a temporary table.
    create TABLE T2 as SELECT * from T
3) Try this PL/SQL block.
    declare cursor c_v is select C from V;

     FOR cv in c_v LOOP
          Insert into T2 SELECT * FROM T where T.C = cv.C and ROWNUM = 1;
     END LOOP;
4) DELETE ALL repeated.
     DELETE FROM T  where C in (select C from V)
5) Add only one repeated row.
    insert into T select * from T2;
6) Drop TABLE T2;

7) Drop VIEW V;

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This was last published in March 2002

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