


How Can I Remove Duplicate Rows from an Oracle Table While Keeping One Unique Row?
Removing Duplicate Rows in Oracle Tables: A Practical Approach
During Oracle table population, duplicate rows can unintentionally arise, preventing the creation of a primary key. This article details a method to efficiently remove these duplicates while retaining a single unique row.
Solution: Utilizing the rowid
Pseudocolumn
Oracle's rowid
pseudocolumn provides a unique identifier for each row. We leverage this to identify and delete redundant entries.
The following SQL statement uses rowid
to achieve this:
DELETE FROM your_table WHERE rowid NOT IN (SELECT MIN(rowid) FROM your_table GROUP BY column1, column2, column3);
This query deletes rows whose rowid
doesn't correspond to the minimum rowid
within each group of duplicates. The GROUP BY
clause defines the grouping based on the specified columns (column1, column2, column3). Only one row per unique combination of these column values will remain.
For precise duplicate removal, consider including all columns in the GROUP BY
clause. Adjust the column names to match your specific table structure.
This approach ensures only unique records are retained, paving the way for primary key creation and other database operations.
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