Hello! I'm trying to join a data file to a shapefile (Census tracts), and then export the result for additional analyses. Some tracts have no/excluded data (too few observations). When I join the files, these appear as <Null> in the shapefile's attribute table, but after exporting, they revert to 0s (their columns contain numerical values). Any way to maintain their <Null> status following export? It's a substantial number of columns, so a batch way to do this would be preferred.