How Can I Efficiently Remove Duplicate Rows from an Oracle Table?

Data Integrity in Oracle: Eliminating Duplicate Rows

Duplicate entries in Oracle tables can compromise data integrity, especially when establishing primary keys. This article outlines a solution to effectively remove these duplicates.

Leveraging the rowid Pseudocolumn

Oracle's rowid pseudocolumn offers a unique identifier for each row. This allows for a precise deletion strategy:

<code class="language-sql">DELETE FROM your_table
WHERE rowid NOT IN
(SELECT MIN(rowid)
FROM your_table
GROUP BY column1, column2, column3);</code>

Here's a breakdown:

• your_table: The table containing the duplicate rows.
• column1, column2, column3: The columns defining uniqueness. Add more columns to the GROUP BY clause as needed.
• The subquery selects the minimum rowid for each unique combination of columns.
• The NOT IN clause deletes all rows whose rowid isn't the minimum, leaving only one instance of each unique record.

This approach efficiently cleanses your table of duplicate entries, ensuring data integrity for subsequent operations.

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