How to compare data from database with data in files based on keys

My task is to check if data in the database is all in an Excel file and spit out the missing rows into another Excel. I have database reader and file reader but not sure how to join those together so that I can discard the data from database that is found in the file and keep the data that is not found in the file. The data matching is based on a text column and a date column. (Not same names but I can make same names if necessary).