Looking up a column in an external table

[Anthony stark]

Hi Experts,

I have a column from an external spreadsheet called [sites] with 6,200+ values (which might change from time to time). I also have the same colum [sites], in a data table in spotfire that i am trying to compare to the external column, and if the have they same value [sites], then exclude it from the [sites] calculation in the spotfire data table. Any idea how i can go about doing this I dont think a case statement would suffice because of the amount of values involved, i m trying to fing a way where the external column can be brought into spotfire and checked against the same column in spotfire.

Thanks in advance

[Anthony stark]

Any ideas