data-konzept

'According to database design best practices, a SQL Server table should not contain duplicate rows. During the database design process primary keys should be created to eliminate duplicate rows. However, sometimes we need to work with databases where these rules are not followed or exceptions are possible (when these rules are bypassed knowingly). For example, when a staging table is used and data is loaded from different sources where duplicate rows are possible. When the loading process completes, table should be cleaned or clean data should be loaded to a permanent table, so after that duplicates are no longer needed. Therefore an issue concerning the removal of duplicates from the loading table arises. In this tip let's examine some ways to solve data de-duplication needs.'...

https://www.mssqltips.com/sqlservertip/4486/find-and-remove-duplicate-rows-from-a-sql-server-table/