is there a way of extracting differences between two spreadsheets?

Assuming you have a unique identifier for each record, or can create a unique identifier by concatenating two or more fields then you can use an =MATCH() function to match the key field in the good (old) file with the same key field in the bad file.

If there's a match then the row number of the match will be given otherwise if there's no match the function will return a #N/A error. All you need to do then is filter the data for the #N/A rows, select them all and delete them.

You can utilize MS Query.
Or PowerQuery if you have access to it.

You'll need to perform what's known as Anti-Join.

MS Query (see section about Subtract Join for extracting data that doesn't match any record in the other table).
https://support.microsoft.com/en-ca/...icrosoft-query

For PowerQuery, read article written by Ken Puls.
https://www.excelguru.ca/blog/2015/1...n-power-query/

Originally Posted by centraltickets

hi Richard,

That's really helpful, thank you.

So I could use the email addresses as a unique identifier. So would the smaller of the csv files into say, sheet 2 of the larger csv and then run that function in a new column on the latter?

Thanks again.

Yes the email address would be ideal.

I see that my original was confusing and may have confused.

You need to put the =MATCH formula in a spare column in the sheet which contains the larger number of records - i.e. the bad file. This Match will look up the email large file email address in the email field of the smaller file and find where that exists. Where it finds a match then it will return a row number and hence you know it exists in both files. Hence filter for the #N/As and delete all those rows.