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I had written a plsql block which will delete the duplicate data in a table. Since the logic that I have written is wrong, some original data is also deleted and the changes are committed. Please advice me on how I can revert the committed data changes and also advice me on how to delete duplicates

Barbaros Özhan
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Mahesh Naidu
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  • you may look up `as of timestamp systimestamp - interval ..` for the first part of the question. There are lots of samples for the second one. – Barbaros Özhan Jul 28 '20 at 13:33

2 Answers2

2

You could do it using Flashback feature.

1.Flashback by SCN

SELECT column_list
FROM table_name
AS OF SCN scn_number;

2.Flashback by TIMESTAMP

SELECT column_list
FROM table_name
AS OF TIMESTAMP TO_TIMESTAMP('the timestamp value');

To get current_scn and systimestamp, query:

SELECT current_scn, SYSTIMESTAMP
FROM v$database;

Let's see an example:

To flashback the table to the old scn, use FLASHBACK TABLE..TO SCN clause.

SQL> DROP TABLE string_ex PURGE;

Table dropped.

SQL> CREATE TABLE string_ex (sl_ps_code VARCHAR2(20) );

Table created.

SQL> INSERT INTO string_ex (sl_ps_code) VALUES ('AR14ASM0002');

1 row created.

SQL> INSERT INTO string_ex (sl_ps_code) VALUES ('AR14SFT0018');

1 row created.

SQL> INSERT INTO string_ex (sl_ps_code) VALUES ('AR14SFT0019');

1 row created.

SQL> INSERT INTO string_ex (sl_ps_code) VALUES ('AR14SFT0062');

1 row created.

SQL> COMMIT;

Commit complete.

SQL> SELECT current_scn, SYSTIMESTAMP FROM v$database;

         CURRENT_SCN SYSTIMESTAMP
-------------------- --------------------------------------------
      13818123201277 29-OCT-14 03.02.17.419000 PM +05:30

SQL> SELECT current_scn, SYSTIMESTAMP FROM v$database;

         CURRENT_SCN SYSTIMESTAMP
-------------------- --------------------------------------------
      13818123201280 29-OCT-14 03.02.22.785000 PM +05:30

SQL> SELECT current_scn, SYSTIMESTAMP FROM v$database;

         CURRENT_SCN SYSTIMESTAMP
-------------------- --------------------------------------------
      13818123201282 29-OCT-14 03.02.26.781000 PM +05:30

SQL> SELECT * FROM string_ex;

SL_PS_CODE
---------------
AR14ASM0002
AR14SFT0018
AR14SFT0019
AR14SFT0062

SQL>

I have four rows in the table.

SQL> ALTER TABLE string_ex ENABLE ROW MOVEMENT;

Table altered.

SQL>

Row movement is required.

SQL> DELETE FROM string_ex WHERE ROWNUM =1;

1 row deleted.

SQL>
SQL> COMMIT;

Commit complete.

SQL>
SQL> SELECT * FROM string_ex;

SL_PS_CODE
---------------
AR14SFT0018
AR14SFT0019
AR14SFT0062

I deleted a row now and committed the changes.

SQL> FLASHBACK TABLE string_ex TO SCN 13818123201277;

Flashback complete.
Flashback is complete

SQL> SELECT * FROM string_ex;

SL_PS_CODE
---------------
AR14ASM0002
AR14SFT0018
AR14SFT0019
AR14SFT0062

SQL>

I now have my table to old state and the row is back

By: How to rollback my DB changes after a commit?

Caique Andrade
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1

Flasback query will be used to revert the commited changes in oracle. Please google on how to user falsback query in oracle

Mahesh
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