Find semi-last record in a table

Hi experts

I have prepared a report to see which of our companies use exchange rates that are updated on a daily basis and which not. The problem is with the formula I want to use:

find the last starting date in a currency table and then check the difference with the semi-last. I want to know how I can find the semi-last starting date.


Here is the code I use to get the last starting date:

G8=NL("Last","Currency Exchange Rate","Starting Date","Currency Code",F8,,,,,,,,,,,,,,,"datasource=",$D8,"Company=",$E8)


And this what I have been experimenting with for the semi-last:

=NL("Last","Currency Exchange Rate","Starting Date","Currency Code",F8,"-Starting Date",G8-1,,,,,,,,,,,,,"datasource=",$D8,"Company=",$E8)

Thanks!