Delete Duplicate Rows

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Sur Delete Duplicate Rows

How to Delete Duplicate Rows in a Database

Understanding Duplicate Data

Duplicate rows in a database can cause inefficiencies, inaccuracies, and increased storage usage. They often occur due to data entry errors, system glitches, or poor database design. Identifying and removing duplicates ensures data integrity and optimal performance.

Methods to Delete Duplicate Rows

Below are common techniques to delete duplicate rows in SQL databases:

Method	Description
Using `DISTINCT` with a Temporary Table	Copy non-duplicate rows to a new table, then replace the original table.
Using `ROW_NUMBER()` (SQL Server, PostgreSQL)	Assign a row number to each record and delete rows with numbers greater than 1.
Using `GROUP BY` and `HAVING`	Group rows by key columns and delete those with a count greater than 1.

Best Practices to Avoid Duplicates

Prevent duplicates by enforcing unique constraints, validating data before insertion, and normalizing databases. Regular audits and cleanup scripts can also help maintain a clean dataset.