Checking for duplicate data before importing.

Good Afternoon,
I currently have a table that houses data for the entire year. The data is call volume for a call center. Each day we add the previous day's data into the table. An example of the data is:

QueueName Pass StartingVolume CallsPlaced CallsContacted DateofData

This data is imported from excel spreadsheets that are saved at the end of each day automatically. The problem I am having is when people use Get External Data to import the excel spreadsheet into the table they are sometimes importing a day that was already done. I would like it to see if that data is already in there before it imports. However to do this it would need to check all the fields as sometimes the queue name and the number of calls can be the same but the pass or other data can be different so it needs to check every column to determine if that row is already in there.