Append new data only

Hi all,

I'm connectint to a web page and importing xml.

I want to be able to download the data for yesterday and append to a historical table, rather than refreshing all the data each day.

I've tried to append to a new query but it seems that this historical query would need to be refreshed which defeats the object.

The dataset is too large to refresh in total on a daily basis.

Does anyone have any ideas?

Thanks

Mike