How do I… Identify and delete duplicates from SQL Server tables?
Posted June 4th, 2008 by Andrew PopoffDuplicate records in a database are bad. You can’t tolerate them. At the very least, they’ll produce misleading analysis. At the worst, they’ll totally wreck everything. Your application will probably run, but everything it generates will be suspect. You have to find them and delete them or your client might just delete you!
Of course, the applications you develop prevent duplicates from the get go — pat yourself on the back. However, your keen insight into the potential problems duplicates pose won’t help you if you inherit a legacy application or have to import dirty data. The good news is that finding and deleting duplicate records in Microsoft’s SQL Server isn’t a difficult task. However, determining just what constitutes a duplicate can be a bit tricky.
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