I have created a Data Transformation Service (DTS) in SQL Server using the import/export data wizard, saved it as a Visual Basic file and then upgraded it to Vb.Net. I am importing data from an excel file into a SQL Server table. The basics are working fine, but I now want to improve the importing function. I want to disallow duplicate entries so that the same data cannot be entered more than once - except for if the data for a specific record has changed - and in this case I want to add the record, and move its original value to another table. Does anyone have an idea how I can go about this?