The simplest way to delete duplicates and compare two result sets in SQL Server

http://weblogs.sqlteam.com/mladenp/archive/2009/01/05/The-simplest-way-to-delete-duplicates-and-compare-two-result.aspx

Một cách khác

http://www.andyscott.id.au/blog/Deleting-Duplicate-rows-the-smart-way-using-OVER-PARTITION-in-MS-SQL