I'm trying to backup data from 12 different tables with a c# script. The backup tables have already been created and have been populated with the original table data. The problem that I'm in is that the script is supposed to check the backup table against the original table and just add the new rows that have been added to the new table.

For example:
table_1 is the original with its backup being table_1_bk (the same for the other 11 tables). At this point they have the same data, by the end of everyday new data is added to table_1 so when the script is run at eod it needs to detect the new rows and add them to the backup table. Any suggestions are greatly appreciated